diff --git a/.github/workflows/ci-linux.yml b/.github/workflows/ci-linux.yml
index 1854483a42..e4db5c0e1b 100644
--- a/.github/workflows/ci-linux.yml
+++ b/.github/workflows/ci-linux.yml
@@ -21,7 +21,7 @@ jobs:
     - uses: ./.github/actions/install-essential-dependences
     - uses: ./.github/actions/init-make-config
       with:
-        options: --cc=gcc --cxx=g++
+        options: --cc=gcc --cxx=g++ --werror
     - name: compile
       run: |
            make -j ${{env.proc_num}}
@@ -61,7 +61,7 @@ jobs:
     - uses: ./.github/actions/install-all-dependences
     - uses: ./.github/actions/init-make-config
       with:
-       options: --cc=gcc --cxx=g++ --with-thrift --with-glog --with-rdma  --with-debug-bthread-sche-safety --with-debug-lock --with-bthread-tracer
+       options: --cc=gcc --cxx=g++ --with-thrift --with-glog --with-rdma  --with-debug-bthread-sche-safety --with-debug-lock --with-bthread-tracer --werror
     - name: compile
       run: |
         make -j ${{env.proc_num}}
@@ -95,7 +95,7 @@ jobs:
     - uses: ./.github/actions/install-essential-dependences
     - uses: ./.github/actions/init-make-config
       with:
-        options: --cc=clang --cxx=clang++
+        options: --cc=clang --cxx=clang++ --werror
     - name: compile
       run: |
            make -j ${{env.proc_num}}
@@ -135,7 +135,7 @@ jobs:
     - uses: ./.github/actions/install-all-dependences
     - uses: ./.github/actions/init-make-config
       with:
-        options: --cc=clang --cxx=clang++ --with-thrift --with-glog --with-rdma  --with-debug-bthread-sche-safety --with-debug-lock --with-bthread-tracer
+        options: --cc=clang --cxx=clang++ --with-thrift --with-glog --with-rdma  --with-debug-bthread-sche-safety --with-debug-lock --with-bthread-tracer --werror
     - name: compile
       run: |
            make -j ${{env.proc_num}}
diff --git a/BUILD.bazel b/BUILD.bazel
index 0e2e66edd2..84ae6bd775 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -29,7 +29,6 @@ COPTS = [
     "-D__STDC_FORMAT_MACROS",
     "-D__STDC_LIMIT_MACROS",
     "-D__STDC_CONSTANT_MACROS",
-    "-DGFLAGS_NS=google",
 ] + select({
     "//bazel/config:brpc_with_glog": ["-DBRPC_WITH_GLOG=1"],
     "//conditions:default": ["-DBRPC_WITH_GLOG=0"],
diff --git a/CMakeLists.txt b/CMakeLists.txt
index a6b7716b29..30076bf26e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -39,7 +39,7 @@ if(POLICY CMP0042)
     cmake_policy(SET CMP0042 NEW)
 endif()
 
-set(BRPC_VERSION 1.11.0)
+set(BRPC_VERSION 1.12.1)
 
 SET(CPACK_GENERATOR "DEB")
 SET(CPACK_DEBIAN_PACKAGE_MAINTAINER "brpc authors")
@@ -114,17 +114,6 @@ list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 
 find_package(GFLAGS REQUIRED)
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
-
 include_directories(
     ${PROJECT_SOURCE_DIR}/src
     ${CMAKE_CURRENT_BINARY_DIR}
@@ -144,7 +133,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     set(CMAKE_CPP_FLAGS "${CMAKE_CPP_FLAGS} -Wno-deprecated-declarations -Wno-inconsistent-missing-override")
 endif()
 
-set(CMAKE_CPP_FLAGS "${CMAKE_CPP_FLAGS} ${DEFINE_CLOCK_GETTIME} -DBRPC_WITH_GLOG=${WITH_GLOG_VAL} -DBRPC_WITH_RDMA=${WITH_RDMA_VAL} -DGFLAGS_NS=${GFLAGS_NS} -DBRPC_DEBUG_BTHREAD_SCHE_SAFETY=${WITH_DEBUG_BTHREAD_SCHE_SAFETY_VAL} -DBRPC_DEBUG_LOCK=${WITH_DEBUG_LOCK_VAL}")
+set(CMAKE_CPP_FLAGS "${CMAKE_CPP_FLAGS} ${DEFINE_CLOCK_GETTIME} -DBRPC_WITH_GLOG=${WITH_GLOG_VAL} -DBRPC_WITH_RDMA=${WITH_RDMA_VAL} -DBRPC_DEBUG_BTHREAD_SCHE_SAFETY=${WITH_DEBUG_BTHREAD_SCHE_SAFETY_VAL} -DBRPC_DEBUG_LOCK=${WITH_DEBUG_LOCK_VAL}")
 if(WITH_MESALINK)
     set(CMAKE_CPP_FLAGS "${CMAKE_CPP_FLAGS} -DUSE_MESALINK")
 endif()
diff --git a/MODULE.bazel b/MODULE.bazel
index e53146aefb..07955f2565 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -1,6 +1,6 @@
 module(
   name = 'brpc',
-  version = '1.11.0',
+  version = '1.12.1',
   compatibility_level = 1,
 )
 
diff --git a/NOTICE b/NOTICE
index 9939c15699..55a2c50bd0 100644
--- a/NOTICE
+++ b/NOTICE
@@ -1,5 +1,5 @@
 Apache bRPC
-Copyright 2018-2024 The Apache Software Foundation
+Copyright 2018-2025 The Apache Software Foundation
 
 This product includes software developed at
 The Apache Software Foundation (http://www.apache.org/).
diff --git a/RELEASE_VERSION b/RELEASE_VERSION
index 1cac385c6c..f8f4f03b3d 100644
--- a/RELEASE_VERSION
+++ b/RELEASE_VERSION
@@ -1 +1 @@
-1.11.0
+1.12.1
diff --git a/config_brpc.sh b/config_brpc.sh
index 2563b0e28e..25f506fe04 100755
--- a/config_brpc.sh
+++ b/config_brpc.sh
@@ -38,7 +38,7 @@ else
     LDD=ldd
 fi
 
-TEMP=`getopt -o v: --long headers:,libs:,cc:,cxx:,with-glog,with-thrift,with-rdma,with-mesalink,with-bthread-tracer,with-debug-bthread-sche-safety,with-debug-lock,nodebugsymbols -n 'config_brpc' -- "$@"`
+TEMP=`getopt -o v: --long headers:,libs:,cc:,cxx:,with-glog,with-thrift,with-rdma,with-mesalink,with-bthread-tracer,with-debug-bthread-sche-safety,with-debug-lock,nodebugsymbols,werror -n 'config_brpc' -- "$@"`
 WITH_GLOG=0
 WITH_THRIFT=0
 WITH_RDMA=0
@@ -46,6 +46,7 @@ WITH_MESALINK=0
 WITH_BTHREAD_TRACER=0
 BRPC_DEBUG_BTHREAD_SCHE_SAFETY=0
 DEBUGSYMBOLS=-g
+WERROR=
 BRPC_DEBUG_LOCK=0
 
 if [ $? != 0 ] ; then >&2 $ECHO "Terminating..."; exit 1 ; fi
@@ -74,6 +75,7 @@ while true; do
         --with-debug-bthread-sche-safety ) BRPC_DEBUG_BTHREAD_SCHE_SAFETY=1; shift 1 ;;
         --with-debug-lock ) BRPC_DEBUG_LOCK=1; shift 1 ;;
         --nodebugsymbols ) DEBUGSYMBOLS=; shift 1 ;;
+        --werror ) WERROR=-Werror; shift 1 ;;
         -- ) shift; break ;;
         * ) break ;;
     esac
@@ -259,15 +261,6 @@ fi
 PROTOC=$(find_bin_or_die protoc)
 
 GFLAGS_HDR=$(find_dir_of_header_or_die gflags/gflags.h)
-# namespace of gflags may not be google, grep it from source.
-GFLAGS_NS=$(grep "namespace [_A-Za-z0-9]\+ {" $GFLAGS_HDR/gflags/gflags_declare.h | head -1 | awk '{print $2}')
-if [ "$GFLAGS_NS" = "GFLAGS_NAMESPACE" ]; then
-    GFLAGS_NS=$(grep "#define GFLAGS_NAMESPACE [_A-Za-z0-9]\+" $GFLAGS_HDR/gflags/gflags_declare.h | head -1 | awk '{print $3}')
-fi
-if [ -z "$GFLAGS_NS" ]; then
-    >&2 $ECHO "Fail to grep namespace of gflags source $GFLAGS_HDR/gflags/gflags_declare.h"
-    exit 1
-fi
 
 PROTOBUF_HDR=$(find_dir_of_header_or_die google/protobuf/message.h)
 PROTOBUF_VERSION=$(grep '#define GOOGLE_PROTOBUF_VERSION [0-9]\+' $PROTOBUF_HDR/google/protobuf/stubs/common.h | awk '{print $3}')
@@ -432,7 +425,7 @@ append_to_output "STATIC_LINKINGS=$STATIC_LINKINGS"
 append_to_output "DYNAMIC_LINKINGS=$DYNAMIC_LINKINGS"
 
 # CPP means C PreProcessing, not C PlusPlus
-CPPFLAGS="${CPPFLAGS}  -DBRPC_WITH_GLOG=$WITH_GLOG -DGFLAGS_NS=$GFLAGS_NS -DBRPC_DEBUG_BTHREAD_SCHE_SAFETY=$BRPC_DEBUG_BTHREAD_SCHE_SAFETY -DBRPC_DEBUG_LOCK=$BRPC_DEBUG_LOCK"
+CPPFLAGS="${CPPFLAGS}  -DBRPC_WITH_GLOG=$WITH_GLOG -DBRPC_DEBUG_BTHREAD_SCHE_SAFETY=$BRPC_DEBUG_BTHREAD_SCHE_SAFETY -DBRPC_DEBUG_LOCK=$BRPC_DEBUG_LOCK"
 
 # Avoid over-optimizations of TLS variables by GCC>=4.8
 # See: https://github.com/apache/brpc/issues/1693
@@ -441,6 +434,9 @@ CPPFLAGS="${CPPFLAGS} -D__const__=__unused__"
 if [ ! -z "$DEBUGSYMBOLS" ]; then
     CPPFLAGS="${CPPFLAGS} $DEBUGSYMBOLS"
 fi
+if [ ! -z "$WERROR" ]; then
+    CPPFLAGS="${CPPFLAGS} $WERROR"
+fi
 if [ "$SYSTEM" = "Darwin" ]; then
     CPPFLAGS="${CPPFLAGS} -Wno-deprecated-declarations -Wno-inconsistent-missing-override"
     version=`sw_vers -productVersion | awk -F '.' '{print $1 "." $2}'`
diff --git a/example/BUILD.bazel b/example/BUILD.bazel
index afc525a331..b38cd5a156 100644
--- a/example/BUILD.bazel
+++ b/example/BUILD.bazel
@@ -28,7 +28,6 @@ COPTS = [
     "-fPIC",
     "-Wno-unused-parameter",
     "-fno-omit-frame-pointer",
-    "-DGFLAGS_NS=google",
 ] + select({
     "//bazel/config:brpc_with_glog": ["-DBRPC_WITH_GLOG=1"],
     "//conditions:default": ["-DBRPC_WITH_GLOG=0"],
diff --git a/example/asynchronous_echo_c++/CMakeLists.txt b/example/asynchronous_echo_c++/CMakeLists.txt
index 2946e29963..37cb5f380c 100644
--- a/example/asynchronous_echo_c++/CMakeLists.txt
+++ b/example/asynchronous_echo_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/asynchronous_echo_c++/client.cpp b/example/asynchronous_echo_c++/client.cpp
index e77918cbb8..b52297b4b5 100644
--- a/example/asynchronous_echo_c++/client.cpp
+++ b/example/asynchronous_echo_c++/client.cpp
@@ -51,7 +51,7 @@ void HandleEchoResponse(
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/asynchronous_echo_c++/server.cpp b/example/asynchronous_echo_c++/server.cpp
index 7aad241f6a..dcce19a80b 100644
--- a/example/asynchronous_echo_c++/server.cpp
+++ b/example/asynchronous_echo_c++/server.cpp
@@ -87,7 +87,7 @@ class EchoServiceImpl : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/auto_concurrency_limiter/CMakeLists.txt b/example/auto_concurrency_limiter/CMakeLists.txt
index 4d4802c8d4..a496dd572b 100644
--- a/example/auto_concurrency_limiter/CMakeLists.txt
+++ b/example/auto_concurrency_limiter/CMakeLists.txt
@@ -51,16 +51,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -69,8 +59,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/auto_concurrency_limiter/client.cpp b/example/auto_concurrency_limiter/client.cpp
index 13377f04ba..d33325ddf9 100644
--- a/example/auto_concurrency_limiter/client.cpp
+++ b/example/auto_concurrency_limiter/client.cpp
@@ -215,7 +215,7 @@ void RunCase(test::ControlService_Stub &cntl_stub,
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     Expose();
 
     brpc::Channel channel;
diff --git a/example/auto_concurrency_limiter/server.cpp b/example/auto_concurrency_limiter/server.cpp
index 5d7314548d..61f826fab7 100644
--- a/example/auto_concurrency_limiter/server.cpp
+++ b/example/auto_concurrency_limiter/server.cpp
@@ -271,7 +271,7 @@ class ControlServiceImpl : public test::ControlService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     bthread::FLAGS_bthread_concurrency= FLAGS_server_bthread_concurrency;
 
     brpc::Server server;
diff --git a/example/backup_request_c++/CMakeLists.txt b/example/backup_request_c++/CMakeLists.txt
index 5b91114b50..3c8d34a0a8 100644
--- a/example/backup_request_c++/CMakeLists.txt
+++ b/example/backup_request_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/backup_request_c++/client.cpp b/example/backup_request_c++/client.cpp
index dfbb5856dc..07005e3770 100644
--- a/example/backup_request_c++/client.cpp
+++ b/example/backup_request_c++/client.cpp
@@ -35,7 +35,7 @@ DEFINE_int32(backup_request_ms, 2, "Timeout for sending backup request");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/backup_request_c++/server.cpp b/example/backup_request_c++/server.cpp
index 198120f19b..9bc8a578b2 100644
--- a/example/backup_request_c++/server.cpp
+++ b/example/backup_request_c++/server.cpp
@@ -78,7 +78,7 @@ class SleepyEchoService : public EchoService
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/baidu_proxy_and_generic_call/CMakeLists.txt b/example/baidu_proxy_and_generic_call/CMakeLists.txt
index 88c691dff5..7e34d0a83d 100644
--- a/example/baidu_proxy_and_generic_call/CMakeLists.txt
+++ b/example/baidu_proxy_and_generic_call/CMakeLists.txt
@@ -51,16 +51,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -69,8 +59,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/baidu_proxy_and_generic_call/client.cpp b/example/baidu_proxy_and_generic_call/client.cpp
index d8040740a8..b8fd3101bb 100644
--- a/example/baidu_proxy_and_generic_call/client.cpp
+++ b/example/baidu_proxy_and_generic_call/client.cpp
@@ -34,7 +34,7 @@ DEFINE_int32(interval_ms, 1000, "Milliseconds between consecutive requests");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/baidu_proxy_and_generic_call/proxy.cpp b/example/baidu_proxy_and_generic_call/proxy.cpp
index 81e1176ba2..a7f24fbcc5 100644
--- a/example/baidu_proxy_and_generic_call/proxy.cpp
+++ b/example/baidu_proxy_and_generic_call/proxy.cpp
@@ -111,7 +111,7 @@ class BaiduMasterServiceImpl : public brpc::BaiduMasterService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/baidu_proxy_and_generic_call/server.cpp b/example/baidu_proxy_and_generic_call/server.cpp
index b3f161736e..64d4936696 100644
--- a/example/baidu_proxy_and_generic_call/server.cpp
+++ b/example/baidu_proxy_and_generic_call/server.cpp
@@ -78,7 +78,7 @@ class EchoServiceImpl : public EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/bthread_tag_echo_c++/CMakeLists.txt b/example/bthread_tag_echo_c++/CMakeLists.txt
index 3dd7a24522..d91aa6ca23 100644
--- a/example/bthread_tag_echo_c++/CMakeLists.txt
+++ b/example/bthread_tag_echo_c++/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/bthread_tag_echo_c++/client.cpp b/example/bthread_tag_echo_c++/client.cpp
index 2af1a8a66f..2b5a9e0bb5 100644
--- a/example/bthread_tag_echo_c++/client.cpp
+++ b/example/bthread_tag_echo_c++/client.cpp
@@ -84,7 +84,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/bthread_tag_echo_c++/server.cpp b/example/bthread_tag_echo_c++/server.cpp
index ed4ba4d6c3..0d14bd1dcf 100644
--- a/example/bthread_tag_echo_c++/server.cpp
+++ b/example/bthread_tag_echo_c++/server.cpp
@@ -74,10 +74,10 @@ static void* my_background_task(void*) {
 
 int main(int argc, char* argv[]) {
     std::string help_str = "dummy help infomation";
-    GFLAGS_NS::SetUsageMessage(help_str);
+    GFLAGS_NAMESPACE::SetUsageMessage(help_str);
 
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (FLAGS_h) {
         fprintf(stderr, "%s\n%s\n%s", help_str.c_str(), help_str.c_str(), help_str.c_str());
diff --git a/example/cancel_c++/CMakeLists.txt b/example/cancel_c++/CMakeLists.txt
index d6246c67fe..b8d64ddad5 100644
--- a/example/cancel_c++/CMakeLists.txt
+++ b/example/cancel_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/cancel_c++/client.cpp b/example/cancel_c++/client.cpp
index b1ba1aeb6a..dd23b679e9 100644
--- a/example/cancel_c++/client.cpp
+++ b/example/cancel_c++/client.cpp
@@ -45,7 +45,7 @@ class CancelRPC : public google::protobuf::Closure {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/cancel_c++/server.cpp b/example/cancel_c++/server.cpp
index 5fa5e17acf..b85ec09a97 100644
--- a/example/cancel_c++/server.cpp
+++ b/example/cancel_c++/server.cpp
@@ -73,7 +73,7 @@ class EchoServiceImpl : public EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/cascade_echo_c++/CMakeLists.txt b/example/cascade_echo_c++/CMakeLists.txt
index bfb11025fd..453067b105 100644
--- a/example/cascade_echo_c++/CMakeLists.txt
+++ b/example/cascade_echo_c++/CMakeLists.txt
@@ -57,16 +57,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -75,8 +65,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/cascade_echo_c++/client.cpp b/example/cascade_echo_c++/client.cpp
index cb545b6e32..25a1b52fa7 100644
--- a/example/cascade_echo_c++/client.cpp
+++ b/example/cascade_echo_c++/client.cpp
@@ -87,8 +87,8 @@ void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::SetUsageMessage("Send EchoRequest to server every second");
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::SetUsageMessage("Send EchoRequest to server every second");
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/cascade_echo_c++/server.cpp b/example/cascade_echo_c++/server.cpp
index de19e660fd..c329073c56 100644
--- a/example/cascade_echo_c++/server.cpp
+++ b/example/cascade_echo_c++/server.cpp
@@ -85,8 +85,8 @@ class CascadeEchoService : public EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::SetUsageMessage("A server that may call itself");
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::SetUsageMessage("A server that may call itself");
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/coroutine/coroutine_server.cpp b/example/coroutine/coroutine_server.cpp
index 9df50b04b6..51ef7fcba0 100644
--- a/example/coroutine/coroutine_server.cpp
+++ b/example/coroutine/coroutine_server.cpp
@@ -111,9 +111,9 @@ int main(int argc, char* argv[]) {
     bthread_setconcurrency(BTHREAD_MIN_CONCURRENCY);
 
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     if (FLAGS_enable_coroutine) {
-        GFLAGS_NS::SetCommandLineOption("usercode_in_coroutine", "true");
+        GFLAGS_NAMESPACE::SetCommandLineOption("usercode_in_coroutine", "true");
     }
 
     // Generally you only need one Server.
diff --git a/example/dynamic_partition_echo_c++/CMakeLists.txt b/example/dynamic_partition_echo_c++/CMakeLists.txt
index a5724d2ce8..cf79c8cb09 100644
--- a/example/dynamic_partition_echo_c++/CMakeLists.txt
+++ b/example/dynamic_partition_echo_c++/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/dynamic_partition_echo_c++/client.cpp b/example/dynamic_partition_echo_c++/client.cpp
index 6c83b086ef..fd25514ccd 100644
--- a/example/dynamic_partition_echo_c++/client.cpp
+++ b/example/dynamic_partition_echo_c++/client.cpp
@@ -122,7 +122,7 @@ class MyPartitionParser : public brpc::PartitionParser {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/dynamic_partition_echo_c++/server.cpp b/example/dynamic_partition_echo_c++/server.cpp
index 0047e01c6a..e86affaa91 100644
--- a/example/dynamic_partition_echo_c++/server.cpp
+++ b/example/dynamic_partition_echo_c++/server.cpp
@@ -94,7 +94,7 @@ class EchoServiceImpl : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (FLAGS_server_num <= 0) {
         LOG(ERROR) << "server_num must be positive";
diff --git a/example/echo_c++/CMakeLists.txt b/example/echo_c++/CMakeLists.txt
index 54fdd5707a..02d2477914 100644
--- a/example/echo_c++/CMakeLists.txt
+++ b/example/echo_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/echo_c++/client.cpp b/example/echo_c++/client.cpp
index 337aa6e90d..3cc83f7203 100644
--- a/example/echo_c++/client.cpp
+++ b/example/echo_c++/client.cpp
@@ -34,7 +34,7 @@ DEFINE_int32(interval_ms, 1000, "Milliseconds between consecutive requests");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/echo_c++/server.cpp b/example/echo_c++/server.cpp
index d1f0605178..cc0050aea5 100644
--- a/example/echo_c++/server.cpp
+++ b/example/echo_c++/server.cpp
@@ -94,7 +94,7 @@ class EchoServiceImpl : public EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/grpc_c++/CMakeLists.txt b/example/grpc_c++/CMakeLists.txt
index 6250d2aba9..3d947688d2 100644
--- a/example/grpc_c++/CMakeLists.txt
+++ b/example/grpc_c++/CMakeLists.txt
@@ -55,17 +55,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
-
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -74,8 +63,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/grpc_c++/client.cpp b/example/grpc_c++/client.cpp
index 0ce4b90b7c..4318ed885e 100644
--- a/example/grpc_c++/client.cpp
+++ b/example/grpc_c++/client.cpp
@@ -33,9 +33,9 @@ DEFINE_bool(gzip, false, "compress body using gzip");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     if (FLAGS_gzip) {
-        GFLAGS_NS::SetCommandLineOption("http_body_compress_threshold", 0);
+        GFLAGS_NAMESPACE::SetCommandLineOption("http_body_compress_threshold", 0);
     }
     
     // A Channel represents a communication line to a Server. Notice that 
diff --git a/example/grpc_c++/server.cpp b/example/grpc_c++/server.cpp
index 50e21dba76..7658556e65 100644
--- a/example/grpc_c++/server.cpp
+++ b/example/grpc_c++/server.cpp
@@ -47,7 +47,7 @@ class GreeterImpl : public helloworld::Greeter {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/http_c++/CMakeLists.txt b/example/http_c++/CMakeLists.txt
index c5e7d40a5a..66c4deec97 100644
--- a/example/http_c++/CMakeLists.txt
+++ b/example/http_c++/CMakeLists.txt
@@ -62,17 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
-
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -81,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/http_c++/benchmark_http.cpp b/example/http_c++/benchmark_http.cpp
index 3ddcfe14bb..7fc879d190 100644
--- a/example/http_c++/benchmark_http.cpp
+++ b/example/http_c++/benchmark_http.cpp
@@ -74,7 +74,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/http_c++/http_client.cpp b/example/http_c++/http_client.cpp
index d9984c886f..23222dee9b 100644
--- a/example/http_c++/http_client.cpp
+++ b/example/http_c++/http_client.cpp
@@ -38,7 +38,7 @@ DECLARE_bool(http_verbose);
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (argc != 2) {
         LOG(ERROR) << "Usage: ./http_client \"http(s)://www.foo.com\"";
diff --git a/example/http_c++/http_server.cpp b/example/http_c++/http_server.cpp
index 3a806c43ea..05c9a0ee4c 100644
--- a/example/http_c++/http_server.cpp
+++ b/example/http_c++/http_server.cpp
@@ -225,7 +225,7 @@ class HttpSSEServiceImpl : public HttpSSEService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/memcache_c++/CMakeLists.txt b/example/memcache_c++/CMakeLists.txt
index 7236f01c43..e3e70f96b7 100644
--- a/example/memcache_c++/CMakeLists.txt
+++ b/example/memcache_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/memcache_c++/client.cpp b/example/memcache_c++/client.cpp
index 01b03651d3..5f32198867 100644
--- a/example/memcache_c++/client.cpp
+++ b/example/memcache_c++/client.cpp
@@ -101,7 +101,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     if (FLAGS_exptime < 0) {
         FLAGS_exptime = 0;
     }
diff --git a/example/multi_threaded_echo_c++/CMakeLists.txt b/example/multi_threaded_echo_c++/CMakeLists.txt
index 896483afc5..d57886b6f1 100644
--- a/example/multi_threaded_echo_c++/CMakeLists.txt
+++ b/example/multi_threaded_echo_c++/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/multi_threaded_echo_c++/client.cpp b/example/multi_threaded_echo_c++/client.cpp
index 0b7ea28ce1..fa9768c726 100644
--- a/example/multi_threaded_echo_c++/client.cpp
+++ b/example/multi_threaded_echo_c++/client.cpp
@@ -85,7 +85,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/multi_threaded_echo_c++/server.cpp b/example/multi_threaded_echo_c++/server.cpp
index b747487f2a..54ca096016 100644
--- a/example/multi_threaded_echo_c++/server.cpp
+++ b/example/multi_threaded_echo_c++/server.cpp
@@ -56,10 +56,10 @@ DEFINE_bool(h, false, "print help information");
 
 int main(int argc, char* argv[]) {
     std::string help_str = "dummy help infomation";
-    GFLAGS_NS::SetUsageMessage(help_str);
+    GFLAGS_NAMESPACE::SetUsageMessage(help_str);
 
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (FLAGS_h) {
         fprintf(stderr, "%s\n%s\n%s", help_str.c_str(), help_str.c_str(), help_str.c_str());
diff --git a/example/multi_threaded_echo_fns_c++/CMakeLists.txt b/example/multi_threaded_echo_fns_c++/CMakeLists.txt
index c934f7aa88..0805485d95 100644
--- a/example/multi_threaded_echo_fns_c++/CMakeLists.txt
+++ b/example/multi_threaded_echo_fns_c++/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/multi_threaded_echo_fns_c++/client.cpp b/example/multi_threaded_echo_fns_c++/client.cpp
index cec7f0d463..895b3e5523 100644
--- a/example/multi_threaded_echo_fns_c++/client.cpp
+++ b/example/multi_threaded_echo_fns_c++/client.cpp
@@ -91,7 +91,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/multi_threaded_echo_fns_c++/server.cpp b/example/multi_threaded_echo_fns_c++/server.cpp
index c9576e68ca..2e837bbf46 100644
--- a/example/multi_threaded_echo_fns_c++/server.cpp
+++ b/example/multi_threaded_echo_fns_c++/server.cpp
@@ -97,7 +97,7 @@ class EchoServiceImpl : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (FLAGS_server_num <= 0) {
         LOG(ERROR) << "server_num must be positive";
diff --git a/example/nshead_extension_c++/CMakeLists.txt b/example/nshead_extension_c++/CMakeLists.txt
index 5aa496ac63..244bca6876 100644
--- a/example/nshead_extension_c++/CMakeLists.txt
+++ b/example/nshead_extension_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/nshead_extension_c++/client.cpp b/example/nshead_extension_c++/client.cpp
index b5263d5286..bfc48b6f7e 100644
--- a/example/nshead_extension_c++/client.cpp
+++ b/example/nshead_extension_c++/client.cpp
@@ -35,7 +35,7 @@ DEFINE_int32(max_retry, 3, "Max retries(not including the first RPC)");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/nshead_extension_c++/server.cpp b/example/nshead_extension_c++/server.cpp
index b59c2c0442..1cbd57289c 100644
--- a/example/nshead_extension_c++/server.cpp
+++ b/example/nshead_extension_c++/server.cpp
@@ -51,7 +51,7 @@ class MyNsheadProtocol : public brpc::NsheadService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     brpc::Server server;
     brpc::ServerOptions options;
diff --git a/example/nshead_pb_extension_c++/CMakeLists.txt b/example/nshead_pb_extension_c++/CMakeLists.txt
index 0516a9ebe6..b630294965 100644
--- a/example/nshead_pb_extension_c++/CMakeLists.txt
+++ b/example/nshead_pb_extension_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/nshead_pb_extension_c++/client.cpp b/example/nshead_pb_extension_c++/client.cpp
index b5263d5286..bfc48b6f7e 100644
--- a/example/nshead_pb_extension_c++/client.cpp
+++ b/example/nshead_pb_extension_c++/client.cpp
@@ -35,7 +35,7 @@ DEFINE_int32(max_retry, 3, "Max retries(not including the first RPC)");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/nshead_pb_extension_c++/server.cpp b/example/nshead_pb_extension_c++/server.cpp
index 4f67ecd8a6..d87c9a2743 100644
--- a/example/nshead_pb_extension_c++/server.cpp
+++ b/example/nshead_pb_extension_c++/server.cpp
@@ -97,7 +97,7 @@ class MyNsheadProtocol : public brpc::NsheadPbServiceAdaptor {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     brpc::Server server;
     example::EchoServiceImpl echo_service_impl;
diff --git a/example/parallel_echo_c++/CMakeLists.txt b/example/parallel_echo_c++/CMakeLists.txt
index b70d7571be..7cdb412ae5 100644
--- a/example/parallel_echo_c++/CMakeLists.txt
+++ b/example/parallel_echo_c++/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/parallel_echo_c++/client.cpp b/example/parallel_echo_c++/client.cpp
index 933e2b655a..54ce661dd8 100644
--- a/example/parallel_echo_c++/client.cpp
+++ b/example/parallel_echo_c++/client.cpp
@@ -94,7 +94,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/parallel_echo_c++/server.cpp b/example/parallel_echo_c++/server.cpp
index 364b29ed61..c57e0011ce 100644
--- a/example/parallel_echo_c++/server.cpp
+++ b/example/parallel_echo_c++/server.cpp
@@ -52,7 +52,7 @@ class EchoServiceImpl : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/partition_echo_c++/CMakeLists.txt b/example/partition_echo_c++/CMakeLists.txt
index 2e09c388ca..4d845c724e 100644
--- a/example/partition_echo_c++/CMakeLists.txt
+++ b/example/partition_echo_c++/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/partition_echo_c++/client.cpp b/example/partition_echo_c++/client.cpp
index 83fa001e7a..b60a63d032 100644
--- a/example/partition_echo_c++/client.cpp
+++ b/example/partition_echo_c++/client.cpp
@@ -123,7 +123,7 @@ class MyPartitionParser : public brpc::PartitionParser {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/partition_echo_c++/server.cpp b/example/partition_echo_c++/server.cpp
index 4c2053f832..aa65d41b7a 100644
--- a/example/partition_echo_c++/server.cpp
+++ b/example/partition_echo_c++/server.cpp
@@ -94,7 +94,7 @@ class EchoServiceImpl : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (FLAGS_server_num <= 0) {
         LOG(ERROR) << "server_num must be positive";
diff --git a/example/rdma_performance/CMakeLists.txt b/example/rdma_performance/CMakeLists.txt
index de730720be..2812b0b03b 100644
--- a/example/rdma_performance/CMakeLists.txt
+++ b/example/rdma_performance/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,7 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS} -DBRPC_WITH_RDMA=1")
+set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DBRPC_WITH_RDMA=1")
 set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/rdma_performance/client.cpp b/example/rdma_performance/client.cpp
index e6013b55ca..57d0c06c93 100644
--- a/example/rdma_performance/client.cpp
+++ b/example/rdma_performance/client.cpp
@@ -272,7 +272,7 @@ void Test(int thread_num, int attachment_size) {
 }
 
 int main(int argc, char* argv[]) {
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Initialize RDMA environment in advance.
     if (FLAGS_use_rdma) {
diff --git a/example/rdma_performance/server.cpp b/example/rdma_performance/server.cpp
index 9920cbb24d..d3d00057f4 100644
--- a/example/rdma_performance/server.cpp
+++ b/example/rdma_performance/server.cpp
@@ -63,7 +63,7 @@ class PerfTestServiceImpl : public PerfTestService {
 }
 
 int main(int argc, char* argv[]) {
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     brpc::Server server;
     test::PerfTestServiceImpl perf_test_service_impl;
diff --git a/example/redis_c++/CMakeLists.txt b/example/redis_c++/CMakeLists.txt
index fc4745c872..e29dcbeb45 100644
--- a/example/redis_c++/CMakeLists.txt
+++ b/example/redis_c++/CMakeLists.txt
@@ -67,16 +67,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -85,8 +75,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/redis_c++/redis_cli.cpp b/example/redis_c++/redis_cli.cpp
index d4cbf63a95..02124aa34e 100644
--- a/example/redis_c++/redis_cli.cpp
+++ b/example/redis_c++/redis_cli.cpp
@@ -77,7 +77,7 @@ static int cli_getc(FILE *stream) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/redis_c++/redis_press.cpp b/example/redis_c++/redis_press.cpp
index 7c4e5a5c9b..165b8bf1f9 100644
--- a/example/redis_c++/redis_press.cpp
+++ b/example/redis_c++/redis_press.cpp
@@ -97,7 +97,7 @@ static void* sender(void* void_args) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/rpcz_echo_c++/CMakeLists.txt b/example/rpcz_echo_c++/CMakeLists.txt
index e377acc1d1..d1f1d924be 100644
--- a/example/rpcz_echo_c++/CMakeLists.txt
+++ b/example/rpcz_echo_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/rpcz_echo_c++/client.cpp b/example/rpcz_echo_c++/client.cpp
index ad80de0f50..8cb86866fe 100644
--- a/example/rpcz_echo_c++/client.cpp
+++ b/example/rpcz_echo_c++/client.cpp
@@ -37,7 +37,7 @@ DEFINE_int32(interval_ms, 1000, "Milliseconds between consecutive requests");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // brpc::FLAGS_enable_rpcz = true;
     // A Channel represents a communication line to a Server. Notice that 
diff --git a/example/rpcz_echo_c++/server.cpp b/example/rpcz_echo_c++/server.cpp
index 0f5f7f26f5..8503e99583 100644
--- a/example/rpcz_echo_c++/server.cpp
+++ b/example/rpcz_echo_c++/server.cpp
@@ -132,7 +132,7 @@ class EchoServiceImpl : public EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/selective_echo_c++/CMakeLists.txt b/example/selective_echo_c++/CMakeLists.txt
index 4931121821..809bd22a59 100644
--- a/example/selective_echo_c++/CMakeLists.txt
+++ b/example/selective_echo_c++/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/selective_echo_c++/client.cpp b/example/selective_echo_c++/client.cpp
index 99f9f0fd52..6f0c413a2b 100644
--- a/example/selective_echo_c++/client.cpp
+++ b/example/selective_echo_c++/client.cpp
@@ -86,7 +86,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/selective_echo_c++/server.cpp b/example/selective_echo_c++/server.cpp
index cd075ac7a8..0705a32890 100644
--- a/example/selective_echo_c++/server.cpp
+++ b/example/selective_echo_c++/server.cpp
@@ -93,7 +93,7 @@ class EchoServiceImpl : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (FLAGS_server_num <= 0) {
         LOG(ERROR) << "server_num must be positive";
diff --git a/example/session_data_and_thread_local/CMakeLists.txt b/example/session_data_and_thread_local/CMakeLists.txt
index ea1c838174..27f60e58ac 100644
--- a/example/session_data_and_thread_local/CMakeLists.txt
+++ b/example/session_data_and_thread_local/CMakeLists.txt
@@ -62,16 +62,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -80,8 +70,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DBRPC_ENABLE_CPU_PROFILER")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
diff --git a/example/session_data_and_thread_local/client.cpp b/example/session_data_and_thread_local/client.cpp
index f0cc9892a4..f075e70451 100644
--- a/example/session_data_and_thread_local/client.cpp
+++ b/example/session_data_and_thread_local/client.cpp
@@ -85,7 +85,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/session_data_and_thread_local/server.cpp b/example/session_data_and_thread_local/server.cpp
index 5d5efc1c71..c196c33edc 100644
--- a/example/session_data_and_thread_local/server.cpp
+++ b/example/session_data_and_thread_local/server.cpp
@@ -211,7 +211,7 @@ void AsyncJob::run() {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // The factory to create MySessionLocalData. Must be valid when server is running.
     MySessionLocalDataFactory session_local_data_factory;
diff --git a/example/streaming_batch_echo_c++/CMakeLists.txt b/example/streaming_batch_echo_c++/CMakeLists.txt
index 1d152ef9a0..c434067257 100644
--- a/example/streaming_batch_echo_c++/CMakeLists.txt
+++ b/example/streaming_batch_echo_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-        COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-            COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-            OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/streaming_batch_echo_c++/client.cpp b/example/streaming_batch_echo_c++/client.cpp
index ea58a191b8..23f2b06d3a 100644
--- a/example/streaming_batch_echo_c++/client.cpp
+++ b/example/streaming_batch_echo_c++/client.cpp
@@ -55,7 +55,7 @@ class StreamClientReceiver : public brpc::StreamInputHandler {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/streaming_batch_echo_c++/server.cpp b/example/streaming_batch_echo_c++/server.cpp
index 3690344a8f..88ea8981de 100644
--- a/example/streaming_batch_echo_c++/server.cpp
+++ b/example/streaming_batch_echo_c++/server.cpp
@@ -91,7 +91,7 @@ class StreamingBatchEchoService : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/streaming_echo_c++/CMakeLists.txt b/example/streaming_echo_c++/CMakeLists.txt
index ebefaf4f06..571991e0b4 100644
--- a/example/streaming_echo_c++/CMakeLists.txt
+++ b/example/streaming_echo_c++/CMakeLists.txt
@@ -58,16 +58,6 @@ if((NOT GFLAGS_INCLUDE_PATH) OR (NOT GFLAGS_LIBRARY))
 endif()
 include_directories(${GFLAGS_INCLUDE_PATH})
 
-execute_process(
-    COMMAND bash -c "grep \"namespace [_A-Za-z0-9]\\+ {\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $2}' | tr -d '\n'"
-    OUTPUT_VARIABLE GFLAGS_NS
-)
-if(${GFLAGS_NS} STREQUAL "GFLAGS_NAMESPACE")
-    execute_process(
-        COMMAND bash -c "grep \"#define GFLAGS_NAMESPACE [_A-Za-z0-9]\\+\" ${GFLAGS_INCLUDE_PATH}/gflags/gflags_declare.h | head -1 | awk '{print $3}' | tr -d '\n'"
-        OUTPUT_VARIABLE GFLAGS_NS
-    )
-endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     include(CheckFunctionExists)
     CHECK_FUNCTION_EXISTS(clock_gettime HAVE_CLOCK_GETTIME)
@@ -76,8 +66,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     endif()
 endif()
 
-set(CMAKE_CPP_FLAGS "${DEFINE_CLOCK_GETTIME} -DGFLAGS_NS=${GFLAGS_NS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
+set(CMAKE_CXX_FLAGS "${DEFINE_CLOCK_GETTIME} -DNDEBUG -O2 -D__const__=__unused__ -pipe -W -Wall -Wno-unused-parameter -fPIC -fno-omit-frame-pointer")
 
 if(CMAKE_VERSION VERSION_LESS "3.1.3")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
diff --git a/example/streaming_echo_c++/client.cpp b/example/streaming_echo_c++/client.cpp
index d593625138..619f579a61 100644
--- a/example/streaming_echo_c++/client.cpp
+++ b/example/streaming_echo_c++/client.cpp
@@ -31,7 +31,7 @@ DEFINE_int32(max_retry, 3, "Max retries(not including the first RPC)");
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/example/streaming_echo_c++/server.cpp b/example/streaming_echo_c++/server.cpp
index 072105c70a..808d88d03b 100644
--- a/example/streaming_echo_c++/server.cpp
+++ b/example/streaming_echo_c++/server.cpp
@@ -82,7 +82,7 @@ class StreamingEchoService : public example::EchoService {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // Generally you only need one Server.
     brpc::Server server;
diff --git a/example/thrift_extension_c++/client2.cpp b/example/thrift_extension_c++/client2.cpp
index 276dbac065..c6caa0a890 100644
--- a/example/thrift_extension_c++/client2.cpp
+++ b/example/thrift_extension_c++/client2.cpp
@@ -79,7 +79,7 @@ static void* sender(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     // A Channel represents a communication line to a Server. Notice that 
     // Channel is thread-safe and can be shared by all threads in your program.
diff --git a/package/rpm/brpc.spec b/package/rpm/brpc.spec
index f70daf1873..85eb549d0f 100644
--- a/package/rpm/brpc.spec
+++ b/package/rpm/brpc.spec
@@ -18,7 +18,7 @@
 #
 
 Name:		brpc
-Version:	1.11.0
+Version:	1.12.1
 Release:	1%{?dist}
 Summary:	Industrial-grade RPC framework using C++ Language.
 
diff --git a/src/brpc/builtin/flags_service.cpp b/src/brpc/builtin/flags_service.cpp
index 27ad5bc48b..1c9075c54e 100644
--- a/src/brpc/builtin/flags_service.cpp
+++ b/src/brpc/builtin/flags_service.cpp
@@ -63,7 +63,7 @@ static std::string HtmlReplace(const std::string& s) {
     }
 }
 
-static void PrintFlag(std::ostream& os, const GFLAGS_NS::CommandLineFlagInfo& flag,
+static void PrintFlag(std::ostream& os, const GFLAGS_NAMESPACE::CommandLineFlagInfo& flag,
                       bool use_html) {
     if (use_html) {
         os << "<tr><td>";
@@ -108,8 +108,8 @@ void FlagsService::set_value_page(Controller* cntl,
                                   ::google::protobuf::Closure* done) {
     ClosureGuard done_guard(done);
     const std::string& name = cntl->http_request().unresolved_path();
-    GFLAGS_NS::CommandLineFlagInfo info;
-    if (!GFLAGS_NS::GetCommandLineFlagInfo(name.c_str(), &info)) {
+    GFLAGS_NAMESPACE::CommandLineFlagInfo info;
+    if (!GFLAGS_NAMESPACE::GetCommandLineFlagInfo(name.c_str(), &info)) {
         cntl->SetFailed(ENOMETHOD, "No such gflag");
         return;
     }
@@ -155,8 +155,8 @@ void FlagsService::default_method(::google::protobuf::RpcController* cntl_base,
         if (use_html && cntl->http_request().uri().GetQuery("withform")) {
             return set_value_page(cntl, done_guard.release());
         }
-        GFLAGS_NS::CommandLineFlagInfo info;
-        if (!GFLAGS_NS::GetCommandLineFlagInfo(constraint.c_str(), &info)) {
+        GFLAGS_NAMESPACE::CommandLineFlagInfo info;
+        if (!GFLAGS_NAMESPACE::GetCommandLineFlagInfo(constraint.c_str(), &info)) {
             cntl->SetFailed(ENOMETHOD, "No such gflag");
             return;
         }
@@ -169,8 +169,8 @@ void FlagsService::default_method(::google::protobuf::RpcController* cntl_base,
                             constraint.c_str());
             return;
         }
-        if (GFLAGS_NS::SetCommandLineOption(constraint.c_str(),
-                                         value_str->c_str()).empty()) {
+        if (GFLAGS_NAMESPACE::SetCommandLineOption(constraint.c_str(),
+                                                   value_str->c_str()).empty()) {
             cntl->SetFailed(EPERM, "Fail to set `%s' to %s",
                             constraint.c_str(),
                             (value_str->empty() ? "empty string" : value_str->c_str()));
@@ -218,8 +218,8 @@ void FlagsService::default_method(::google::protobuf::RpcController* cntl_base,
         // Only exact names. We don't have to iterate all flags in this case.
         for (std::set<std::string>::iterator it = exact.begin();
              it != exact.end(); ++it) {
-            GFLAGS_NS::CommandLineFlagInfo info;
-            if (GFLAGS_NS::GetCommandLineFlagInfo(it->c_str(), &info)) {
+            GFLAGS_NAMESPACE::CommandLineFlagInfo info;
+            if (GFLAGS_NAMESPACE::GetCommandLineFlagInfo(it->c_str(), &info)) {
                 PrintFlag(os, info, use_html);
                 os << '\n';
             }
@@ -227,10 +227,10 @@ void FlagsService::default_method(::google::protobuf::RpcController* cntl_base,
 
     } else {
         // Iterate all flags and filter.
-        std::vector<GFLAGS_NS::CommandLineFlagInfo> flag_list;
+        std::vector<GFLAGS_NAMESPACE::CommandLineFlagInfo> flag_list;
         flag_list.reserve(128);
-        GFLAGS_NS::GetAllFlags(&flag_list);
-        for (std::vector<GFLAGS_NS::CommandLineFlagInfo>::iterator
+        GFLAGS_NAMESPACE::GetAllFlags(&flag_list);
+        for (std::vector<GFLAGS_NAMESPACE::CommandLineFlagInfo>::iterator
                  it = flag_list.begin(); it != flag_list.end(); ++it) {
             if (!constraint.empty() &&
                 exact.find(it->name) == exact.end() &&
diff --git a/src/brpc/builtin/rpcz_service.cpp b/src/brpc/builtin/rpcz_service.cpp
index b9e056376a..d9121eb555 100644
--- a/src/brpc/builtin/rpcz_service.cpp
+++ b/src/brpc/builtin/rpcz_service.cpp
@@ -65,7 +65,7 @@ void RpczService::enable(::google::protobuf::RpcController* cntl_base,
     const bool use_html = UseHTML(cntl->http_request());
     cntl->http_response().set_content_type(
         use_html ? "text/html" : "text/plain");
-    if (!GFLAGS_NS::SetCommandLineOption("enable_rpcz", "true").empty()) {
+    if (!GFLAGS_NAMESPACE::SetCommandLineOption("enable_rpcz", "true").empty()) {
         if (use_html) {
             // Redirect to /rpcz
             cntl->response_attachment().append(
@@ -94,7 +94,7 @@ void RpczService::disable(::google::protobuf::RpcController* cntl_base,
     const bool use_html = UseHTML(cntl->http_request());
     cntl->http_response().set_content_type(
         use_html ? "text/html" : "text/plain");
-    if (!GFLAGS_NS::SetCommandLineOption("enable_rpcz", "false").empty()) {
+    if (!GFLAGS_NAMESPACE::SetCommandLineOption("enable_rpcz", "false").empty()) {
         if (use_html) {
             // Redirect to /rpcz
             cntl->response_attachment().append(
diff --git a/src/brpc/input_messenger.cpp b/src/brpc/input_messenger.cpp
index b28c704415..afb8fb3f5e 100644
--- a/src/brpc/input_messenger.cpp
+++ b/src/brpc/input_messenger.cpp
@@ -57,13 +57,20 @@ DEFINE_bool(socket_keepalive, false,
             "Enable keepalive of sockets if this value is true");
 
 DEFINE_int32(socket_keepalive_idle_s, -1,
-             "Set idle time of sockets before keepalive if this value is positive");
+             "Set idle time for socket keepalive in seconds if this value is positive");
 
 DEFINE_int32(socket_keepalive_interval_s, -1,
-             "Set interval of sockets between keepalives if this value is positive");
+             "Set interval between keepalives in seconds if this value is positive");
 
 DEFINE_int32(socket_keepalive_count, -1,
-             "Set number of keepalives of sockets before close if this value is positive");
+             "Set number of keepalives before death if this value is positive");
+
+DEFINE_int32(socket_tcp_user_timeout_ms, -1,
+             "If this value is positive, set number of milliseconds that transmitted "
+             "data may remain unacknowledged, or bufferred data may remain untransmitted "
+             "(due to zero window size) before TCP will forcibly close the corresponding "
+             "connection and return ETIMEDOUT to the application. Only linux supports "
+             "TCP_USER_TIMEOUT.");
 
 DECLARE_bool(usercode_in_pthread);
 DECLARE_bool(usercode_in_coroutine);
@@ -501,6 +508,7 @@ int InputMessenger::Create(const butil::EndPoint& remote_side,
         options.keepalive_options->keepalive_count
             = FLAGS_socket_keepalive_count;
     }
+    options.tcp_user_timeout_ms = FLAGS_socket_tcp_user_timeout_ms;
     return Socket::Create(options, id);
 }
 
@@ -535,6 +543,9 @@ int InputMessenger::Create(SocketOptions options, SocketId* id) {
                 = FLAGS_socket_keepalive_count;
         }
     }
+    if (options.tcp_user_timeout_ms <= 0) {
+        options.tcp_user_timeout_ms = FLAGS_socket_tcp_user_timeout_ms;
+    }
     return Socket::Create(options, id);
 }
 
diff --git a/src/brpc/memcache.h b/src/brpc/memcache.h
index 535516ed20..daedd49861 100644
--- a/src/brpc/memcache.h
+++ b/src/brpc/memcache.h
@@ -196,7 +196,7 @@ class MemcacheResponse : public NonreflectableMessage<MemcacheResponse> {
     void Clear() override;
     bool IsInitialized() const PB_527_OVERRIDE;
   
-    size_t ByteSizeLong() const;
+    size_t ByteSizeLong() const override;
     bool MergePartialFromCodedStream(
         ::google::protobuf::io::CodedInputStream* input) PB_310_OVERRIDE;
     void SerializeWithCachedSizes(
diff --git a/src/brpc/policy/http2_rpc_protocol.cpp b/src/brpc/policy/http2_rpc_protocol.cpp
index 1fd93bf7bf..e202d32bc2 100644
--- a/src/brpc/policy/http2_rpc_protocol.cpp
+++ b/src/brpc/policy/http2_rpc_protocol.cpp
@@ -740,9 +740,13 @@ H2ParseResult H2StreamContext::OnData(
         }
     }
 
-    const int64_t acc = _deferred_window_update.fetch_add(frag_size, butil::memory_order_relaxed) + frag_size;
+    int64_t acc = frag_size +
+        _deferred_window_update.fetch_add(frag_size, butil::memory_order_relaxed);
+    int64_t quota = static_cast<int64_t>(
+        _conn_ctx->local_settings().stream_window_size /
+        (_conn_ctx->VolatilePendingStreamSize() + 1));
     // Allocate the quota of the window to each stream.
-    if (acc >= static_cast<int64_t>(_conn_ctx->local_settings().stream_window_size) / (_conn_ctx->VolatilePendingStreamSize() + 1)) {
+    if (acc >= quota) {
         if (acc > _conn_ctx->local_settings().stream_window_size) {
             LOG(ERROR) << "Fail to satisfy the stream-level flow control policy";
             return MakeH2Error(H2_FLOW_CONTROL_ERROR, frame_head.stream_id);
diff --git a/src/brpc/policy/http_rpc_protocol.cpp b/src/brpc/policy/http_rpc_protocol.cpp
index 2dd18076fb..444be39708 100644
--- a/src/brpc/policy/http_rpc_protocol.cpp
+++ b/src/brpc/policy/http_rpc_protocol.cpp
@@ -1457,9 +1457,9 @@ void ProcessHttpRequest(InputMessageBase *msg) {
         return svc->CallMethod(md, cntl, NULL, NULL, done);
     }
     
-    const Server::MethodProperty* const sp =
+    const Server::MethodProperty* const mp =
         FindMethodPropertyByURI(path, server, &req_header._unresolved_path);
-    if (NULL == sp) {
+    if (NULL == mp) {
         if (security_mode) {
             std::string escape_path;
             WebEscape(path, &escape_path);
@@ -1468,36 +1468,36 @@ void ProcessHttpRequest(InputMessageBase *msg) {
             cntl->SetFailed(ENOMETHOD, "Fail to find method on `%s'", path.c_str());
         }
         return;
-    } else if (sp->service->GetDescriptor() == BadMethodService::descriptor()) {
+    } else if (mp->service->GetDescriptor() == BadMethodService::descriptor()) {
         BadMethodRequest breq;
         BadMethodResponse bres;
         butil::StringSplitter split(path.c_str(), '/');
         breq.set_service_name(std::string(split.field(), split.length()));
-        sp->service->CallMethod(sp->method, cntl, &breq, &bres, NULL);
+        mp->service->CallMethod(mp->method, cntl, &breq, &bres, NULL);
         return;
     }
     // Switch to service-specific error.
     non_service_error.release();
-    MethodStatus* method_status = sp->status;
+    MethodStatus* method_status = mp->status;
     resp_sender.set_method_status(method_status);
     if (method_status) {
         int rejected_cc = 0;
         if (!method_status->OnRequested(&rejected_cc)) {
             cntl->SetFailed(ELIMIT, "Rejected by %s's ConcurrencyLimiter, concurrency=%d",
-                            sp->method->full_name().c_str(), rejected_cc);
+                            mp->method->full_name().c_str(), rejected_cc);
             return;
         }
     }
     
     if (span) {
-        span->ResetServerSpanName(sp->method->full_name());
+        span->ResetServerSpanName(mp->method->full_name());
     }
     // NOTE: accesses to builtin services are not counted as part of
     // concurrency, therefore are not limited by ServerOptions.max_concurrency.
-    if (!sp->is_builtin_service && !sp->params.is_tabbed) {
+    if (!mp->is_builtin_service && !mp->params.is_tabbed) {
         if (socket->is_overcrowded() &&
             !server->options().ignore_eovercrowded &&
-            !sp->ignore_eovercrowded) {
+            !mp->ignore_eovercrowded) {
             cntl->SetFailed(EOVERCROWDED, "Connection to %s is overcrowded",
                             butil::endpoint2str(socket->remote_side()).c_str());
             return;
@@ -1522,8 +1522,8 @@ void ProcessHttpRequest(InputMessageBase *msg) {
         return;
     }
 
-    google::protobuf::Service* svc = sp->service;
-    const google::protobuf::MethodDescriptor* method = sp->method;
+    google::protobuf::Service* svc = mp->service;
+    const google::protobuf::MethodDescriptor* method = mp->method;
     accessor.set_method(method);
     RpcPBMessages* messages = server->options().rpc_pb_message_factory->Get(*svc, *method);;
     resp_sender.set_messages(messages);
@@ -1535,7 +1535,7 @@ void ProcessHttpRequest(InputMessageBase *msg) {
         cntl->SetFailed("Fail to new req or res");
         return;
     }
-    if (sp->params.allow_http_body_to_pb &&
+    if (mp->params.allow_http_body_to_pb &&
         method->input_type()->field_count() > 0) {
         // A protobuf service. No matter if Content-type is set to
         // applcation/json or body is empty, we have to treat body as a json
@@ -1604,10 +1604,10 @@ void ProcessHttpRequest(InputMessageBase *msg) {
                 butil::IOBufAsZeroCopyInputStream wrapper(req_body);
                 std::string err;
                 json2pb::Json2PbOptions options;
-                options.base64_to_bytes = sp->params.pb_bytes_to_base64;
-                options.array_to_single_repeated = sp->params.pb_single_repeated_to_array;
-                cntl->set_pb_bytes_to_base64(sp->params.pb_bytes_to_base64);
-                cntl->set_pb_single_repeated_to_array(sp->params.pb_single_repeated_to_array);
+                options.base64_to_bytes = mp->params.pb_bytes_to_base64;
+                options.array_to_single_repeated = mp->params.pb_single_repeated_to_array;
+                cntl->set_pb_bytes_to_base64(mp->params.pb_bytes_to_base64);
+                cntl->set_pb_single_repeated_to_array(mp->params.pb_single_repeated_to_array);
                 if (!json2pb::JsonToProtoMessage(&wrapper, req, options, &err)) {
                     cntl->SetFailed(EREQUEST, "Fail to parse http body as %s, %s",
                                     req->GetDescriptor()->full_name().c_str(), err.c_str());
diff --git a/src/brpc/rdma/block_pool.cpp b/src/brpc/rdma/block_pool.cpp
index 54e47da457..aef94150ba 100644
--- a/src/brpc/rdma/block_pool.cpp
+++ b/src/brpc/rdma/block_pool.cpp
@@ -46,8 +46,8 @@ static RegisterCallback g_cb = NULL;
 static const size_t BYTES_IN_MB = 1048576;
 
 static const int BLOCK_DEFAULT = 0; // 8KB
-static const int BLOCK_LARGE = 1;  // 64KB
-static const int BLOCK_HUGE = 2;  // 2MB
+// static const int BLOCK_LARGE = 1;  // 64KB
+// static const int BLOCK_HUGE = 2;  // 2MB
 static const int BLOCK_SIZE_COUNT = 3;
 static size_t g_block_size[BLOCK_SIZE_COUNT] = { 8192, 65536, 2 * BYTES_IN_MB };
 
diff --git a/src/brpc/rdma/rdma_endpoint.cpp b/src/brpc/rdma/rdma_endpoint.cpp
index 4d83deacf7..2750b756d3 100644
--- a/src/brpc/rdma/rdma_endpoint.cpp
+++ b/src/brpc/rdma/rdma_endpoint.cpp
@@ -60,8 +60,6 @@ DEFINE_bool(rdma_trace_verbose, false, "Print log message verbosely");
 BRPC_VALIDATE_GFLAG(rdma_trace_verbose, brpc::PassValidate);
 
 static const size_t IOBUF_BLOCK_HEADER_LEN = 32; // implementation-dependent
-static const size_t IOBUF_BLOCK_DEFAULT_PAYLOAD =
-        butil::IOBuf::DEFAULT_BLOCK_SIZE - IOBUF_BLOCK_HEADER_LEN;
 
 // DO NOT change this value unless you know the safe value!!!
 // This is the number of reserved WRs in SQ/RQ for pure ACK.
@@ -79,14 +77,14 @@ static const size_t RESERVED_WR_NUM = 3;
 static const char* MAGIC_STR = "RDMA";
 static const size_t MAGIC_STR_LEN = 4;
 static const size_t HELLO_MSG_LEN_MIN = 40;
-static const size_t HELLO_MSG_LEN_MAX = 4096;
+// static const size_t HELLO_MSG_LEN_MAX = 4096;
 static const size_t ACK_MSG_LEN = 4;
 static uint16_t g_rdma_hello_msg_len = 40;  // In Byte
 static uint16_t g_rdma_hello_version = 2;
 static uint16_t g_rdma_impl_version = 1;
 static uint32_t g_rdma_recv_block_size = 0;
 
-static const uint32_t MAX_INLINE_DATA = 64;
+// static const uint32_t MAX_INLINE_DATA = 64;
 static const uint8_t MAX_HOP_LIMIT = 16;
 static const uint8_t TIMEOUT = 14;
 static const uint8_t RETRY_CNT = 7;
@@ -1021,7 +1019,7 @@ int RdmaEndpoint::PostRecv(uint32_t num, bool zerocopy) {
                 PLOG(WARNING) << "Fail to allocate rbuf";
                 return -1;
             } else {
-                CHECK(size == g_rdma_recv_block_size) << size;
+                CHECK(static_cast<uint32_t>(size) == g_rdma_recv_block_size) << size;
             }
         }
         if (DoPostRecv(_rbuf_data[_rq_received], g_rdma_recv_block_size) < 0) {
diff --git a/src/brpc/rdma/rdma_helper.cpp b/src/brpc/rdma/rdma_helper.cpp
index cf1cce9505..a64eba0aa7 100644
--- a/src/brpc/rdma/rdma_helper.cpp
+++ b/src/brpc/rdma/rdma_helper.cpp
@@ -94,7 +94,7 @@ DEFINE_string(rdma_device, "", "The name of the HCA device used "
 DEFINE_int32(rdma_port, 1, "The port number to use. For RoCE, it is always 1.");
 DEFINE_int32(rdma_gid_index, -1, "The GID index to use. -1 means using the last one.");
 
-static const size_t SYSFS_SIZE = 4096;
+// static const size_t SYSFS_SIZE = 4096;
 static ibv_device** g_devices = NULL;
 static ibv_context* g_context = NULL;
 static SocketId g_async_socket;
diff --git a/src/brpc/rpc_dump.cpp b/src/brpc/rpc_dump.cpp
index bf3d7fc8e9..4686713cd2 100644
--- a/src/brpc/rpc_dump.cpp
+++ b/src/brpc/rpc_dump.cpp
@@ -139,7 +139,7 @@ void SampledRequest::destroy() {
 // Save gflags which could be reloaded at anytime.
 void RpcDumpContext::SaveFlags() {
     std::string dir;
-    CHECK(GFLAGS_NS::GetCommandLineOption("rpc_dump_dir", &dir));
+    CHECK(GFLAGS_NAMESPACE::GetCommandLineOption("rpc_dump_dir", &dir));
     
     const size_t pos = dir.find("<app>");
     if (pos != std::string::npos) {
diff --git a/src/brpc/socket.cpp b/src/brpc/socket.cpp
index 0201a97880..ac4c6892c0 100644
--- a/src/brpc/socket.cpp
+++ b/src/brpc/socket.cpp
@@ -492,6 +492,7 @@ Socket::Socket(Forbidden f)
     , _stream_set(NULL)
     , _total_streams_unconsumed_size(0)
     , _ninflight_app_health_check(0)
+    , _tcp_user_timeout_ms(-1)
     , _http_request_method(HTTP_METHOD_GET) {
     CreateVarsOnce();
     pthread_mutex_init(&_id_wait_list_mutex, NULL);
@@ -597,6 +598,21 @@ int Socket::ResetFileDescriptor(int fd) {
     // turn off nagling.
     // OK to fail, namely unix domain socket does not support this.
     butil::make_no_delay(fd);
+
+    SetSocketOptions(fd);
+
+    if (_on_edge_triggered_events) {
+        if (_io_event.AddConsumer(fd) != 0) {
+            PLOG(ERROR) << "Fail to add SocketId=" << id() 
+                        << " into EventDispatcher";
+            _fd.store(-1, butil::memory_order_release);
+            return -1;
+        }
+    }
+    return 0;
+}
+
+void Socket::SetSocketOptions(int fd) {
     if (_tos > 0 &&
         setsockopt(fd, IPPROTO_IP, IP_TOS, &_tos, sizeof(_tos)) != 0) {
         PLOG(ERROR) << "Fail to set tos of fd=" << fd << " to " << _tos;
@@ -618,27 +634,21 @@ int Socket::ResetFileDescriptor(int fd) {
         }
     }
 
-    EnableKeepaliveIfNeeded(fd);
-
-    if (_on_edge_triggered_events) {
-        if (_io_event.AddConsumer(fd) != 0) {
-            PLOG(ERROR) << "Fail to add SocketId=" << id() 
-                        << " into EventDispatcher";
-            _fd.store(-1, butil::memory_order_release);
-            return -1;
+#if defined(OS_LINUX)
+    if (_tcp_user_timeout_ms > 0) {
+        if (setsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT,
+                       &_tcp_user_timeout_ms, sizeof(_tcp_user_timeout_ms)) != 0) {
+            PLOG(ERROR) << "Fail to set TCP_USER_TIMEOUT of fd=" << fd;
         }
     }
-    return 0;
-}
+#endif
 
-void Socket::EnableKeepaliveIfNeeded(int fd) {
     if (!_keepalive_options) {
         return;
     }
 
     int keepalive = 1;
-    if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive,
-                   sizeof(keepalive)) != 0) {
+    if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof(keepalive)) != 0) {
         PLOG(ERROR) << "Fail to set keepalive of fd=" << fd;
         return;
     }
@@ -782,6 +792,7 @@ int Socket::OnCreated(const SocketOptions& options) {
     _last_writetime_us.store(cpuwide_now, butil::memory_order_relaxed);
     _unwritten_bytes.store(0, butil::memory_order_relaxed);
     _keepalive_options = options.keepalive_options;
+    _tcp_user_timeout_ms = options.tcp_user_timeout_ms;
     CHECK(NULL == _write_head.load(butil::memory_order_relaxed));
     _is_write_shutdown = false;
     int fd = options.fd;
@@ -1388,7 +1399,7 @@ int Socket::CheckConnected(int sockfd) {
         butil::EndPoint local_point;
         CHECK_EQ(0, butil::get_local_side(sockfd, &local_point));
         LOG(INFO) << "Connected to " << remote_side()
-                  << " via fd=" << (int)sockfd << " SocketId=" << id()
+                  << " via fd=" << sockfd << " SocketId=" << id()
                   << " local_side=" << local_point;
     }
 
@@ -2501,6 +2512,16 @@ void Socket::DebugSocket(std::ostream& os, SocketId id) {
 #endif
     }
 
+#if defined(OS_LINUX)
+    {
+        int tcp_user_timeout = 0;
+        socklen_t len = sizeof(tcp_user_timeout);
+        if (getsockopt(fd, SOL_TCP, TCP_USER_TIMEOUT, &tcp_user_timeout, &len) == 0) {
+            os << "\ntcp_user_timeout=" << tcp_user_timeout;
+        }
+    }
+#endif
+
 #if defined(OS_MACOSX)
     struct tcp_connection_info ti;
     socklen_t len = sizeof(ti);
diff --git a/src/brpc/socket.h b/src/brpc/socket.h
index 2a6ab748f2..a84c0abdcf 100644
--- a/src/brpc/socket.h
+++ b/src/brpc/socket.h
@@ -234,60 +234,57 @@ struct SocketSSLContext {
 };
 
 struct SocketKeepaliveOptions {
-    SocketKeepaliveOptions()
-        : keepalive_idle_s(-1)
-        , keepalive_interval_s(-1)
-        , keepalive_count(-1)
-        {}
     // Start keeplives after this period.
-    int keepalive_idle_s;
+    int keepalive_idle_s{-1};
     // Interval between keepalives.
-    int keepalive_interval_s;
+    int keepalive_interval_s{-1};
     // Number of keepalives before death.
-    int keepalive_count;
+    int keepalive_count{-1};
 };
 
 // TODO: Comment fields
 struct SocketOptions {
-    SocketOptions();
-
     // If `fd' is non-negative, set `fd' to be non-blocking and take the
     // ownership. Socket will close the fd(if needed) and call
     // user->BeforeRecycle() before recycling.
-    int fd;
+    int fd{-1};
     butil::EndPoint remote_side;
     // If `connect_on_create' is true and `fd' is less than 0,
     // a client connection will be established to remote_side()
     // regarding deadline `connect_abstime' when Socket is being created.
     // Default: false, means that a connection will be established
     // on first write.
-    bool connect_on_create;
+    bool connect_on_create{false};
     // Default: NULL, means no timeout.
-    const timespec* connect_abstime;
-    SocketUser* user;
+    const timespec* connect_abstime{NULL};
+    SocketUser* user{NULL};
     // When *edge-triggered* events happen on the file descriptor, callback
     // `on_edge_triggered_events' will be called. Inside the callback, user
     // shall read fd() in non-blocking mode until all data has been read
     // or EAGAIN is met, otherwise the callback will not be called again
     // until new data arrives. The callback will not be called from more than
     // one thread at any time.
-    void (*on_edge_triggered_events)(Socket*);
-    int health_check_interval_s;
+    void (*on_edge_triggered_events)(Socket*){NULL};
+    int health_check_interval_s{-1};
     // Only accept ssl connection.
-    bool force_ssl;
+    bool force_ssl{false};
     std::shared_ptr<SocketSSLContext> initial_ssl_ctx;
-    bool use_rdma;
-    bthread_keytable_pool_t* keytable_pool;
-    SocketConnection* conn;
+    bool use_rdma{false};
+    bthread_keytable_pool_t* keytable_pool{NULL};
+    SocketConnection* conn{NULL};
     std::shared_ptr<AppConnect> app_connect;
     // The created socket will set parsing_context with this value.
-    Destroyable* initial_parsing_context;
+    Destroyable* initial_parsing_context{NULL};
 
     // Socket keepalive related options.
     // Refer to `SocketKeepaliveOptions' for details.
     std::shared_ptr<SocketKeepaliveOptions> keepalive_options;
+    // https://github.com/apache/brpc/issues/1154
+    // https://github.com/grpc/grpc/pull/16419/files
+    // Only linux supports TCP_USER_TIMEOUT.
+    int tcp_user_timeout_ms{ -1};
     // Tag of this socket
-    bthread_tag_t bthread_tag;
+    bthread_tag_t bthread_tag{BTHREAD_TAG_DEFAULT};
 };
 
 // Abstractions on reading from and writing into file descriptors.
@@ -725,7 +722,7 @@ friend void DereferenceSocket(Socket*);
 
     int ResetFileDescriptor(int fd);
 
-    void EnableKeepaliveIfNeeded(int fd);
+    void SetSocketOptions(int fd);
 
     // Wait until nref hits `expected_nref' and reset some internal resources.
     int WaitAndReset(int32_t expected_nref);
@@ -973,6 +970,15 @@ friend void DereferenceSocket(Socket*);
     // non-NULL means that keepalive is on.
     std::shared_ptr<SocketKeepaliveOptions> _keepalive_options;
 
+    // Only linux supports TCP_USER_TIMEOUT.
+    // When the value is greater than 0, it specifies the maximum
+    // amount of time in milliseconds that transmitted data may
+    // remain unacknowledged, or bufferred data may remain
+    // untransmitted (due to zero window size) before TCP will
+    // forcibly close the corresponding connection and return
+    // ETIMEDOUT to the application.
+    int _tcp_user_timeout_ms;
+
     HttpMethod _http_request_method;
 };
 
diff --git a/src/brpc/socket_inl.h b/src/brpc/socket_inl.h
index d704b90053..ea8a392ef2 100644
--- a/src/brpc/socket_inl.h
+++ b/src/brpc/socket_inl.h
@@ -23,21 +23,6 @@
 
 namespace brpc {
 
-inline SocketOptions::SocketOptions()
-    : fd(-1)
-    , connect_on_create(false)
-    , connect_abstime(NULL)
-    , user(NULL)
-    , on_edge_triggered_events(NULL)
-    , health_check_interval_s(-1)
-    , force_ssl(false)
-    , use_rdma(false)
-    , keytable_pool(NULL)
-    , conn(NULL)
-    , app_connect(NULL)
-    , initial_parsing_context(NULL)
-    , bthread_tag(BTHREAD_TAG_DEFAULT) {}
-
 inline bool Socket::MoreReadEvents(int* progress) {
     // Fail to CAS means that new events arrived.
     return !_nevent.compare_exchange_strong(
diff --git a/src/brpc/thrift_message.h b/src/brpc/thrift_message.h
index 881b5cf77d..e31c941968 100644
--- a/src/brpc/thrift_message.h
+++ b/src/brpc/thrift_message.h
@@ -81,7 +81,7 @@ friend class ThriftStub;
     void Swap(ThriftFramedMessage* other);
 
     // implements Message ----------------------------------------------
-    void MergeFrom(const ThriftFramedMessage& from);
+    void MergeFrom(const ThriftFramedMessage& from) override;
     void Clear() override;
 
     size_t ByteSizeLong() const override;
diff --git a/src/brpc/versioned_ref_with_id.h b/src/brpc/versioned_ref_with_id.h
index 23ea0e0ad1..e7c3ef8d71 100644
--- a/src/brpc/versioned_ref_with_id.h
+++ b/src/brpc/versioned_ref_with_id.h
@@ -211,7 +211,7 @@ class VersionedRefWithId {
     // Create a VersionedRefWithId, put the identifier into `id'.
     // `args' will be passed to OnCreated() directly.
     // Returns 0 on success, -1 otherwise.
-    template<typename ... Args>
+    template<typename... Args>
     static int Create(VRefId* id, Args&&... args);
 
     // Place the VersionedRefWithId associated with identifier `id' into
@@ -350,7 +350,7 @@ void DereferenceVersionedRefWithId(T* r) {
 }
 
 template <typename T>
-template<typename ... Args>
+template<typename... Args>
 int VersionedRefWithId<T>::Create(VRefId* id, Args&&... args) {
     resource_id_t slot;
     T* const t = butil::get_resource(&slot, Forbidden());
diff --git a/src/bthread/bthread.cpp b/src/bthread/bthread.cpp
index 3de7265705..e124f4bc6f 100644
--- a/src/bthread/bthread.cpp
+++ b/src/bthread/bthread.cpp
@@ -24,6 +24,7 @@
 #include "butil/macros.h"                       // BAIDU_CASSERT
 #include "butil/logging.h"
 #include "butil/thread_local.h"
+#include "butil/reloadable_flags.h"
 #include "bthread/task_group.h"                // TaskGroup
 #include "bthread/task_control.h"              // TaskControl
 #include "bthread/timer_thread.h"
@@ -32,47 +33,34 @@
 
 namespace bthread {
 
+static bool validate_bthread_concurrency(const char*, int32_t val) {
+    // bthread_setconcurrency sets the flag on success path which should
+    // not be strictly in a validator. But it's OK for a int flag.
+    return bthread_setconcurrency(val) == 0;
+}
+static bool validate_bthread_min_concurrency(const char*, int32_t val);
+static bool validate_bthread_current_tag(const char*, int32_t val);
+static bool validate_bthread_concurrency_by_tag(const char*, int32_t val);
+
 DEFINE_int32(bthread_concurrency, 8 + BTHREAD_EPOLL_THREAD_NUM,
              "Number of pthread workers");
+BUTIL_VALIDATE_GFLAG(bthread_concurrency, validate_bthread_concurrency);
 
 DEFINE_int32(bthread_min_concurrency, 0,
             "Initial number of pthread workers which will be added on-demand."
             " The laziness is disabled when this value is non-positive,"
             " and workers will be created eagerly according to -bthread_concurrency and bthread_setconcurrency(). ");
+BUTIL_VALIDATE_GFLAG(bthread_min_concurrency, validate_bthread_min_concurrency);
 
 DEFINE_int32(bthread_current_tag, BTHREAD_TAG_INVALID, "Set bthread concurrency for this tag");
+BUTIL_VALIDATE_GFLAG(bthread_current_tag, validate_bthread_current_tag);
 
 DEFINE_int32(bthread_concurrency_by_tag, 8 + BTHREAD_EPOLL_THREAD_NUM,
              "Number of pthread workers of FLAGS_bthread_current_tag");
+BUTIL_VALIDATE_GFLAG(bthread_concurrency_by_tag, validate_bthread_concurrency_by_tag);
 
 static bool never_set_bthread_concurrency = true;
 
-static bool validate_bthread_concurrency(const char*, int32_t val) {
-    // bthread_setconcurrency sets the flag on success path which should
-    // not be strictly in a validator. But it's OK for a int flag.
-    return bthread_setconcurrency(val) == 0;
-}
-const int ALLOW_UNUSED register_FLAGS_bthread_concurrency = 
-    ::GFLAGS_NS::RegisterFlagValidator(&FLAGS_bthread_concurrency,
-                                    validate_bthread_concurrency);
-
-static bool validate_bthread_min_concurrency(const char*, int32_t val);
-
-const int ALLOW_UNUSED register_FLAGS_bthread_min_concurrency =
-    ::GFLAGS_NS::RegisterFlagValidator(&FLAGS_bthread_min_concurrency,
-                                    validate_bthread_min_concurrency);
-
-static bool validate_bthread_current_tag(const char*, int32_t val);
-
-const int ALLOW_UNUSED register_FLAGS_bthread_current_tag =
-    ::GFLAGS_NS::RegisterFlagValidator(&FLAGS_bthread_current_tag, validate_bthread_current_tag);
-
-static bool validate_bthread_concurrency_by_tag(const char*, int32_t val);
-
-const int ALLOW_UNUSED register_FLAGS_bthread_concurrency_by_tag =
-    ::GFLAGS_NS::RegisterFlagValidator(&FLAGS_bthread_concurrency_by_tag,
-                                       validate_bthread_concurrency_by_tag);
-
 BAIDU_CASSERT(sizeof(TaskControl*) == sizeof(butil::atomic<TaskControl*>), atomic_size_match);
 
 pthread_mutex_t g_task_control_mutex = PTHREAD_MUTEX_INITIALIZER;
diff --git a/src/bthread/task_group.cpp b/src/bthread/task_group.cpp
index 170b273043..361efa5936 100644
--- a/src/bthread/task_group.cpp
+++ b/src/bthread/task_group.cpp
@@ -28,6 +28,7 @@
 #include "butil/fast_rand.h"
 #include "butil/unique_ptr.h"
 #include "butil/third_party/murmurhash3/murmurhash3.h" // fmix64
+#include "butil/reloadable_flags.h"
 #include "bthread/errno.h"                  // ESTOP
 #include "bthread/butex.h"                  // butex_*
 #include "bthread/sys_futex.h"              // futex_wake_private
@@ -41,24 +42,17 @@ namespace bthread {
 static const bthread_attr_t BTHREAD_ATTR_TASKGROUP = {
     BTHREAD_STACKTYPE_UNKNOWN, 0, NULL, BTHREAD_TAG_INVALID };
 
-static bool pass_bool(const char*, bool) { return true; }
-
 DEFINE_bool(show_bthread_creation_in_vars, false, "When this flags is on, The time "
             "from bthread creation to first run will be recorded and shown in /vars");
-const bool ALLOW_UNUSED dummy_show_bthread_creation_in_vars =
-    ::GFLAGS_NS::RegisterFlagValidator(&FLAGS_show_bthread_creation_in_vars,
-                                    pass_bool);
+BUTIL_VALIDATE_GFLAG(show_bthread_creation_in_vars, butil::PassValidate);
 
 DEFINE_bool(show_per_worker_usage_in_vars, false,
             "Show per-worker usage in /vars/bthread_per_worker_usage_<tid>");
-const bool ALLOW_UNUSED dummy_show_per_worker_usage_in_vars =
-    ::GFLAGS_NS::RegisterFlagValidator(&FLAGS_show_per_worker_usage_in_vars,
-                                    pass_bool);
+BUTIL_VALIDATE_GFLAG(show_per_worker_usage_in_vars, butil::PassValidate);
 
 DEFINE_bool(bthread_enable_cpu_clock_stat, false,
             "Enable CPU clock statistics for bthread");
-const bool ALLOW_UNUSED dummy_bthread_enable_cpu_clock_stat =  ::GFLAGS_NS::RegisterFlagValidator(&FLAGS_bthread_enable_cpu_clock_stat,
-                                    pass_bool);
+BUTIL_VALIDATE_GFLAG(bthread_enable_cpu_clock_stat, butil::PassValidate);
 
 BAIDU_VOLATILE_THREAD_LOCAL(TaskGroup*, tls_task_group, NULL);
 // Sync with TaskMeta::local_storage when a bthread is created or destroyed.
@@ -999,7 +993,7 @@ void print_task(std::ostream& os, bthread_t tid) {
     bthread_attr_t attr = BTHREAD_ATTR_NORMAL;
     bool has_tls = false;
     int64_t cpuwide_start_ns = 0;
-    TaskStatistics stat = {0, 0};
+    TaskStatistics stat = {0, 0, 0};
     TaskStatus status = TASK_STATUS_UNKNOWN;
     bool traced = false;
     pid_t worker_tid = 0;
diff --git a/src/butil/logging.cc b/src/butil/logging.cc
index 9f2246092c..a15251b2db 100644
--- a/src/butil/logging.cc
+++ b/src/butil/logging.cc
@@ -102,6 +102,7 @@ typedef pthread_mutex_t* MutexHandle;
 #include "butil/containers/doubly_buffered_data.h"
 #include "butil/memory/singleton.h"
 #include "butil/endpoint.h"
+#include "butil/reloadable_flags.h"
 #ifdef BAIDU_INTERNAL
 #include "butil/comlog_sink.h"
 #endif
@@ -122,8 +123,11 @@ namespace logging {
 
 DEFINE_bool(crash_on_fatal_log, false,
             "Crash process when a FATAL log is printed");
+BUTIL_VALIDATE_GFLAG(crash_on_fatal_log, butil::PassValidate);
+
 DEFINE_bool(print_stack_on_check, true,
             "Print the stack trace when a CHECK was failed");
+BUTIL_VALIDATE_GFLAG(print_stack_on_check, butil::PassValidate);
 
 DEFINE_int32(v, 0, "Show all VLOG(m) messages for m <= this."
              " Overridable by --vmodule.");
@@ -140,6 +144,7 @@ DEFINE_bool(log_bid, true, "Log bthread id");
 DEFINE_int32(minloglevel, 0, "Any log at or above this level will be "
              "displayed. Anything below this level will be silently ignored. "
              "0=INFO 1=NOTICE 2=WARNING 3=ERROR 4=FATAL");
+BUTIL_VALIDATE_GFLAG(minloglevel, butil::NonNegativeInteger);
 
 DEFINE_bool(log_hostname, false, "Add host after pid in each log so"
             " that we know where logs came from when using aggregation tools"
@@ -1930,7 +1935,7 @@ static bool validate_vmodule(const char*, const std::string& vmodule) {
     return on_reset_vmodule(vmodule.c_str()) == 0;
 }
 
-const bool ALLOW_UNUSED validate_vmodule_dummy = GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED validate_vmodule_dummy = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_vmodule, &validate_vmodule);
 
 // [Thread-safe] Reset FLAGS_v.
@@ -1959,26 +1964,7 @@ static bool validate_v(const char*, int32_t v) {
     on_reset_verbose(v);
     return true;
 }
-
-const bool ALLOW_UNUSED validate_v_dummy = GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_v, &validate_v);
-
-static bool PassValidate(const char*, bool) {
-    return true;
-}
-
-const bool ALLOW_UNUSED validate_crash_on_fatal_log =
-    GFLAGS_NS::RegisterFlagValidator(&FLAGS_crash_on_fatal_log, PassValidate);
-
-const bool ALLOW_UNUSED validate_print_stack_on_check =
-    GFLAGS_NS::RegisterFlagValidator(&FLAGS_print_stack_on_check, PassValidate);
-
-static bool NonNegativeInteger(const char*, int32_t v) {
-    return v >= 0;
-}
-
-const bool ALLOW_UNUSED validate_min_log_level = GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_minloglevel, NonNegativeInteger);
+BUTIL_VALIDATE_GFLAG(v, validate_v);
 
 }  // namespace logging
 
diff --git a/src/butil/logging.h b/src/butil/logging.h
index a26ff1e13c..58e369189b 100644
--- a/src/butil/logging.h
+++ b/src/butil/logging.h
@@ -53,23 +53,23 @@
 #  define DPLOG_IF(...) DLOG_IF(__VA_ARGS__)
 #  define DPCHECK(...) DCHECK(__VA_ARGS__)
 #  define DVPLOG(...) DVLOG(__VA_ARGS__)
-# endif
+# endif // DCHECK_IS_ON()
 
 #ifndef LOG_BACKTRACE_IF
 #define LOG_BACKTRACE_IF(severity, condition) LOG_IF(severity, condition)
-#endif
+#endif // LOG_BACKTRACE_IF
 
 #ifndef LOG_BACKTRACE_IF_ONCE
 #define LOG_BACKTRACE_IF_ONCE(severity, condition) LOG_IF_ONCE(severity, condition)
-#endif
+#endif // LOG_BACKTRACE_IF_ONCE
 
 #ifndef LOG_BACKTRACE_FIRST_N
 #define LOG_BACKTRACE_FIRST_N(severity, N) LOG_FIRST_N(severity, N)
-#endif
+#endif // LOG_BACKTRACE_FIRST_N
 
 #ifndef LOG_BACKTRACE_IF_FIRST_N
 #define LOG_BACKTRACE_IF_FIRST_N(severity, condition, N) LOG_IF_FIRST_N(severity, condition, N)
-#endif
+#endif // LOG_BACKTRACE_IF_FIRST_N
 
 
 #define LOG_AT(severity, file, line)                                    \
@@ -485,8 +485,10 @@ void print_vlog_sites(VLogSitePrinter*);
     BAIDU_LAZY_STREAM(LOG_STREAM(severity), LOG_IS_ON(severity))
 #define LOG_IF(severity, condition)                                     \
     BAIDU_LAZY_STREAM(LOG_STREAM(severity), LOG_IS_ON(severity) && (condition))
+#ifndef LOG_BACKTRACE_IF
 #define LOG_BACKTRACE_IF(severity, condition)                               \
     BAIDU_LAZY_STREAM(LOG_STREAM(severity).SetBacktrace(), LOG_IS_ON(severity) && (condition))
+#endif // LOG_BACKTRACE_IF
 
 // FIXME(gejun): Should always crash.
 #define LOG_ASSERT(condition)                                           \
@@ -1185,7 +1187,7 @@ inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) {
 // Select default policy: LOG(ERROR)
 #define NOTIMPLEMENTED_POLICY 4
 #endif
-#endif
+#endif // NOTIMPLEMENTED_POLICY
 
 #if defined(COMPILER_GCC)
 // On Linux, with GCC, we can use __PRETTY_FUNCTION__ to get the demangled name
@@ -1259,9 +1261,11 @@ inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) {
 # define LOG_ONCE(severity) LOG_FIRST_N(severity, 1)
 # define LOG_BACKTRACE_ONCE(severity) LOG_BACKTRACE_FIRST_N(severity, 1)
 # define LOG_IF_ONCE(severity, condition) LOG_IF_FIRST_N(severity, condition, 1)
+#ifndef LOG_BACKTRACE_IF_ONCE
 # define LOG_BACKTRACE_IF_ONCE(severity, condition) \
     LOG_BACKTRACE_IF_FIRST_N(severity, condition, 1)
-#endif
+#endif // LOG_BACKTRACE_IF_ONCE
+#endif // LOG_ONCE
 
 // Print a log after every N calls. First call always prints.
 // Each call to this macro has a cost of relaxed atomic increment.
@@ -1271,7 +1275,7 @@ inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) {
      BAIDU_LOG_IF_EVERY_N_IMPL(LOG_IF, severity, true, N)
 # define LOG_IF_EVERY_N(severity, condition, N)                  \
      BAIDU_LOG_IF_EVERY_N_IMPL(LOG_IF, severity, condition, N)
-#endif
+#endif // LOG_EVERY_N
 
 // Print logs for first N calls.
 // Almost zero overhead when the log was printed for N times
@@ -1279,13 +1283,17 @@ inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) {
 #ifndef LOG_FIRST_N
 # define LOG_FIRST_N(severity, N)                                \
      BAIDU_LOG_IF_FIRST_N_IMPL(LOG_IF, severity, true, N)
+#ifndef LOG_BACKTRACE_FIRST_N
 # define LOG_BACKTRACE_FIRST_N(severity, N)                          \
      BAIDU_LOG_IF_FIRST_N_IMPL(LOG_BACKTRACE_IF, severity, true, N)
+#endif // LOG_BACKTRACE_FIRST_N
 # define LOG_IF_FIRST_N(severity, condition, N)                  \
      BAIDU_LOG_IF_FIRST_N_IMPL(LOG_IF, severity, condition, N)
+#ifndef LOG_BACKTRACE_IF_FIRST_N
 # define LOG_BACKTRACE_IF_FIRST_N(severity, condition, N)            \
      BAIDU_LOG_IF_FIRST_N_IMPL(LOG_BACKTRACE_IF, severity, condition, N)
-#endif
+#endif // LOG_BACKTRACE_IF_FIRST_N
+#endif // LOG_FIRST_N
 
 // Print a log every second. (not present in glog). First call always prints.
 // Each call to this macro has a cost of calling gettimeofday.
@@ -1294,33 +1302,33 @@ inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) {
      BAIDU_LOG_IF_EVERY_SECOND_IMPL(LOG_IF, severity, true)
 # define LOG_IF_EVERY_SECOND(severity, condition)                \
      BAIDU_LOG_IF_EVERY_SECOND_IMPL(LOG_IF, severity, condition)
-#endif
+#endif // LOG_EVERY_SECOND
 
 #ifndef PLOG_EVERY_N
 # define PLOG_EVERY_N(severity, N)                               \
      BAIDU_LOG_IF_EVERY_N_IMPL(PLOG_IF, severity, true, N)
 # define PLOG_IF_EVERY_N(severity, condition, N)                 \
      BAIDU_LOG_IF_EVERY_N_IMPL(PLOG_IF, severity, condition, N)
-#endif
+#endif // PLOG_EVERY_N
 
 #ifndef PLOG_FIRST_N
 # define PLOG_FIRST_N(severity, N)                               \
      BAIDU_LOG_IF_FIRST_N_IMPL(PLOG_IF, severity, true, N)
 # define PLOG_IF_FIRST_N(severity, condition, N)                 \
      BAIDU_LOG_IF_FIRST_N_IMPL(PLOG_IF, severity, condition, N)
-#endif
+#endif // PLOG_FIRST_N
 
 #ifndef PLOG_ONCE
 # define PLOG_ONCE(severity) PLOG_FIRST_N(severity, 1)
 # define PLOG_IF_ONCE(severity, condition) PLOG_IF_FIRST_N(severity, condition, 1)
-#endif
+#endif // PLOG_ONCE
 
 #ifndef PLOG_EVERY_SECOND
 # define PLOG_EVERY_SECOND(severity)                             \
      BAIDU_LOG_IF_EVERY_SECOND_IMPL(PLOG_IF, severity, true)
 # define PLOG_IF_EVERY_SECOND(severity, condition)                       \
      BAIDU_LOG_IF_EVERY_SECOND_IMPL(PLOG_IF, severity, condition)
-#endif
+#endif // PLOG_EVERY_SECOND
 
 // DEBUG_MODE is for uses like
 //   if (DEBUG_MODE) foo.CheckThatFoo();
diff --git a/src/butil/reloadable_flags.h b/src/butil/reloadable_flags.h
index 2cb11e9253..15a9f98d61 100644
--- a/src/butil/reloadable_flags.h
+++ b/src/butil/reloadable_flags.h
@@ -34,12 +34,11 @@
 //
 // This macro does not work for string-flags because they're thread-unsafe to
 // modify directly. To emphasize this, you have to write the validator by
-// yourself and use GFLAGS_NS::GetCommandLineOption() to acess the flag.
-#define BUTIL_VALIDATE_GFLAG(flag, validate_fn)                     \
-    namespace butil_flags {}                                       \
-    const int register_FLAGS_ ## flag ## _dummy                    \
-                 __attribute__((__unused__)) =                     \
-        ::butil::RegisterFlagValidatorOrDieImpl<                   \
+// yourself and use GFLAGS_NAMESPACE::GetCommandLineOption() to acess the flag.
+#define BUTIL_VALIDATE_GFLAG(flag, validate_fn)                   \
+    namespace butil_flags {}                                      \
+    const int ALLOW_UNUSED register_FLAGS_ ## flag ## _dummy =    \
+        ::butil::RegisterFlagValidatorOrDieImpl<                  \
             decltype(FLAGS_##flag)>(&FLAGS_##flag, (validate_fn))
 
 
@@ -55,12 +54,17 @@ bool PositiveInteger(const char*, T v) {
     return v > 0;
 }
 
+template <typename T>
+bool NonNegativeInteger(const char*, T v) {
+    return v >= 0;
+}
+
 template <typename T>
 bool RegisterFlagValidatorOrDieImpl(
     const T* flag, bool (*validate_fn)(const char*, T val)) {
     static_assert(!butil::is_same<std::string, T>::value,
                   "Not support string flags");
-    if (GFLAGS_NS::RegisterFlagValidator(flag, validate_fn)) {
+    if (::GFLAGS_NAMESPACE::RegisterFlagValidator(flag, validate_fn)) {
         return true;
     }
     // Error printed by gflags does not have newline. Add one to it.
diff --git a/src/bvar/gflag.cpp b/src/bvar/gflag.cpp
index a4d11f8af2..5525795cc7 100644
--- a/src/bvar/gflag.cpp
+++ b/src/bvar/gflag.cpp
@@ -34,8 +34,8 @@ GFlag::GFlag(const butil::StringPiece& prefix,
 }
 
 void GFlag::describe(std::ostream& os, bool quote_string) const {
-    GFLAGS_NS::CommandLineFlagInfo info;
-    if (!GFLAGS_NS::GetCommandLineFlagInfo(gflag_name().c_str(), &info)) {
+    GFLAGS_NAMESPACE::CommandLineFlagInfo info;
+    if (!GFLAGS_NAMESPACE::GetCommandLineFlagInfo(gflag_name().c_str(), &info)) {
         if (quote_string) {
             os << '"';
         }
@@ -54,8 +54,8 @@ void GFlag::describe(std::ostream& os, bool quote_string) const {
 
 #ifdef BAIDU_INTERNAL
 void GFlag::get_value(boost::any* value) const {
-    GFLAGS_NS::CommandLineFlagInfo info;
-    if (!GFLAGS_NS::GetCommandLineFlagInfo(gflag_name().c_str(), &info)) {
+    GFLAGS_NAMESPACE::CommandLineFlagInfo info;
+    if (!GFLAGS_NAMESPACE::GetCommandLineFlagInfo(gflag_name().c_str(), &info)) {
         *value = "Unknown gflag=" + gflag_name();
     } else if (info.type == "string") {
         *value = info.current_value;
@@ -78,14 +78,14 @@ void GFlag::get_value(boost::any* value) const {
 
 std::string GFlag::get_value() const {
     std::string str;
-    if (!GFLAGS_NS::GetCommandLineOption(gflag_name().c_str(), &str)) {
+    if (!GFLAGS_NAMESPACE::GetCommandLineOption(gflag_name().c_str(), &str)) {
         return "Unknown gflag=" + gflag_name();
     }
     return str;
 }
 
 bool GFlag::set_value(const char* value) {
-    return !GFLAGS_NS::SetCommandLineOption(gflag_name().c_str(), value).empty();
+    return !GFLAGS_NAMESPACE::SetCommandLineOption(gflag_name().c_str(), value).empty();
 }
 
 }  // namespace bvar
diff --git a/src/bvar/latency_recorder.cpp b/src/bvar/latency_recorder.cpp
index 791bc62693..b4ba0c442e 100644
--- a/src/bvar/latency_recorder.cpp
+++ b/src/bvar/latency_recorder.cpp
@@ -19,25 +19,25 @@
 
 #include <gflags/gflags.h>
 #include "butil/unique_ptr.h"
+#include "butil/reloadable_flags.h"
 #include "bvar/latency_recorder.h"
 
 namespace bvar {
 
+static bool valid_percentile(const char*, int32_t v) {
+    return v > 0 && v < 100;
+}
+
 // Reloading following gflags does not change names of the corresponding bvars.
 // Avoid reloading in practice.
 DEFINE_int32(bvar_latency_p1, 80, "First latency percentile");
+BUTIL_VALIDATE_GFLAG(bvar_latency_p1, valid_percentile);
+
 DEFINE_int32(bvar_latency_p2, 90, "Second latency percentile");
-DEFINE_int32(bvar_latency_p3, 99, "Third latency percentile");
+BUTIL_VALIDATE_GFLAG(bvar_latency_p2, valid_percentile);
 
-static bool valid_percentile(const char*, int32_t v) {
-    return v > 0 && v < 100;
-}
-const bool ALLOW_UNUSED dummy_bvar_latency_p1 = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_bvar_latency_p1, valid_percentile);
-const bool ALLOW_UNUSED dummy_bvar_latency_p2 = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_bvar_latency_p2, valid_percentile);
-const bool ALLOW_UNUSED dummy_bvar_latency_p3 = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_bvar_latency_p3, valid_percentile);
+DEFINE_int32(bvar_latency_p3, 99, "Third latency percentile");
+BUTIL_VALIDATE_GFLAG(bvar_latency_p3, valid_percentile);
 
 namespace detail {
 
diff --git a/src/bvar/mvariable.cpp b/src/bvar/mvariable.cpp
index 033de7faef..86eadf1333 100644
--- a/src/bvar/mvariable.cpp
+++ b/src/bvar/mvariable.cpp
@@ -24,6 +24,7 @@
 #include "butil/containers/flat_map.h"           // butil::FlatMap
 #include "butil/scoped_lock.h"                   // BAIDU_SCOPE_LOCK
 #include "butil/file_util.h"                     // butil::FilePath
+#include "butil/reloadable_flags.h"
 #include "bvar/variable.h"
 #include "bvar/mvariable.h"
 
@@ -35,10 +36,6 @@ DECLARE_bool(bvar_abort_on_same_name);
 
 extern bool s_bvar_may_abort;
 
-DEFINE_int32(bvar_max_multi_dimension_metric_number, 1024, "Max number of multi dimension");
-DEFINE_int32(bvar_max_dump_multi_dimension_metric_number, 1024,
-    "Max number of multi dimension metric number to dump by prometheus rpc service");
-
 static bool validator_bvar_max_multi_dimension_metric_number(const char*, int32_t v) {
     if (v < 1) {
         LOG(ERROR) << "Invalid bvar_max_multi_dimension_metric_number=" << v;
@@ -47,6 +44,10 @@ static bool validator_bvar_max_multi_dimension_metric_number(const char*, int32_
     return true;
 }
 
+DEFINE_int32(bvar_max_multi_dimension_metric_number, 1024, "Max number of multi dimension");
+BUTIL_VALIDATE_GFLAG(bvar_max_multi_dimension_metric_number,
+                     validator_bvar_max_multi_dimension_metric_number);
+
 static bool validator_bvar_max_dump_multi_dimension_metric_number(const char*, int32_t v) {
     if (v < 0) {
         LOG(ERROR) << "Invalid bvar_max_dump_multi_dimension_metric_number=" << v;
@@ -54,13 +55,10 @@ static bool validator_bvar_max_dump_multi_dimension_metric_number(const char*, i
     }
     return true;
 }
-
-
-const bool ALLOW_UNUSED dummp_bvar_max_multi_dimension_metric_number = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_bvar_max_multi_dimension_metric_number, validator_bvar_max_multi_dimension_metric_number);
-
-const bool ALLOW_UNUSED dummp_bvar_max_dump_multi_dimension_metric_number = ::GFLAGS_NS::RegisterFlagValidator(
-  &FLAGS_bvar_max_dump_multi_dimension_metric_number, validator_bvar_max_dump_multi_dimension_metric_number);
+DEFINE_int32(bvar_max_dump_multi_dimension_metric_number, 1024,
+             "Max number of multi dimension metric number to dump by prometheus rpc service");
+BUTIL_VALIDATE_GFLAG(bvar_max_dump_multi_dimension_metric_number,
+                     validator_bvar_max_dump_multi_dimension_metric_number);
 
 class MVarEntry {
 public:
diff --git a/src/bvar/variable.cpp b/src/bvar/variable.cpp
index e4f093555e..0b1e20d9e2 100644
--- a/src/bvar/variable.cpp
+++ b/src/bvar/variable.cpp
@@ -30,6 +30,7 @@
 #include "butil/time.h"                          // milliseconds_from_now
 #include "butil/file_util.h"                     // butil::FilePath
 #include "butil/threading/platform_thread.h"
+#include "butil/reloadable_flags.h"
 #include "bvar/gflag.h"
 #include "bvar/variable.h"
 #include "bvar/mvariable.h"
@@ -43,21 +44,20 @@ DEFINE_bool(save_series, true,
 DEFINE_bool(quote_vector, true,
             "Quote description of Vector<> to make it valid to noah");
 
-DEFINE_bool(bvar_abort_on_same_name, false,
-            "Abort when names of bvar are same");
 // Remember abort request before bvar_abort_on_same_name is initialized.
 bool s_bvar_may_abort = false;
 static bool validate_bvar_abort_on_same_name(const char*, bool v) {
     RELEASE_ASSERT_VERBOSE(!v || !s_bvar_may_abort, "Abort due to name conflict");
     return true;
 }
-const bool ALLOW_UNUSED dummy_bvar_abort_on_same_name = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_bvar_abort_on_same_name, validate_bvar_abort_on_same_name);
+DEFINE_bool(bvar_abort_on_same_name, false, "Abort when names of bvar are same");
+BUTIL_VALIDATE_GFLAG(bvar_abort_on_same_name, validate_bvar_abort_on_same_name);
 
 
 DEFINE_bool(bvar_log_dumpped,  false,
             "[For debugging] print dumpped info"
             " into logstream before call Dumpper");
+BUTIL_VALIDATE_GFLAG(bvar_log_dumpped, butil::PassValidate);
 
 const size_t SUB_MAP_COUNT = 32;  // must be power of 2
 BAIDU_CASSERT(!(SUB_MAP_COUNT & (SUB_MAP_COUNT - 1)), must_be_power_of_2);
@@ -743,39 +743,39 @@ static void* dumping_thread(void*) {
         std::string mbvar_filename;
         std::string mbvar_prefix;
         std::string mbvar_format;
-        if (!GFLAGS_NS::GetCommandLineOption("bvar_dump_file", &filename)) {
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("bvar_dump_file", &filename)) {
             LOG(ERROR) << "Fail to get gflag bvar_dump_file";
             return NULL;
         }
-        if (!GFLAGS_NS::GetCommandLineOption("bvar_dump_include",
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("bvar_dump_include",
                                           &options.white_wildcards)) {
             LOG(ERROR) << "Fail to get gflag bvar_dump_include";
             return NULL;
         }
-        if (!GFLAGS_NS::GetCommandLineOption("bvar_dump_exclude",
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("bvar_dump_exclude",
                                           &options.black_wildcards)) {
             LOG(ERROR) << "Fail to get gflag bvar_dump_exclude";
             return NULL;
         }
-        if (!GFLAGS_NS::GetCommandLineOption("bvar_dump_prefix", &prefix)) {
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("bvar_dump_prefix", &prefix)) {
             LOG(ERROR) << "Fail to get gflag bvar_dump_prefix";
             return NULL;
         }
-        if (!GFLAGS_NS::GetCommandLineOption("bvar_dump_tabs", &tabs)) {
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("bvar_dump_tabs", &tabs)) {
             LOG(ERROR) << "Fail to get gflags bvar_dump_tabs";
             return NULL;
         }
 
         // We can't access string flags directly because it's thread-unsafe.
-        if (!GFLAGS_NS::GetCommandLineOption("mbvar_dump_file", &mbvar_filename)) {
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("mbvar_dump_file", &mbvar_filename)) {
             LOG(ERROR) << "Fail to get gflag mbvar_dump_file";
             return NULL;
         }
-        if (!GFLAGS_NS::GetCommandLineOption("mbvar_dump_prefix", &mbvar_prefix)) {
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("mbvar_dump_prefix", &mbvar_prefix)) {
             LOG(ERROR) << "Fail to get gflag mbvar_dump_prefix";
             return NULL;
         }
-        if (!GFLAGS_NS::GetCommandLineOption("mbvar_dump_format", &mbvar_format)) {
+        if (!GFLAGS_NAMESPACE::GetCommandLineOption("mbvar_dump_format", &mbvar_format)) {
             LOG(ERROR) << "Fail to get gflag mbvar_dump_format";
             return NULL;
         }
@@ -883,8 +883,7 @@ static bool validate_bvar_dump(const char*, bool enabled) {
     }
     return true;
 }
-const bool ALLOW_UNUSED dummy_bvar_dump = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_bvar_dump, validate_bvar_dump);
+BUTIL_VALIDATE_GFLAG(bvar_dump, validate_bvar_dump);
 
 // validators (to make these gflags reloadable in brpc)
 static bool validate_bvar_dump_interval(const char*, int32_t v) {
@@ -898,12 +897,7 @@ static bool validate_bvar_dump_interval(const char*, int32_t v) {
     }
     return true;
 }
-const bool ALLOW_UNUSED dummy_bvar_dump_interval = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_bvar_dump_interval, validate_bvar_dump_interval);
-
-static bool validate_bvar_log_dumpped(const char *, bool) { return true; }
-const bool ALLOW_UNUSED dummy_bvar_log_dumpped = ::GFLAGS_NS::RegisterFlagValidator(
-        &FLAGS_bvar_log_dumpped, validate_bvar_log_dumpped);
+BUTIL_VALIDATE_GFLAG(bvar_dump_interval, validate_bvar_dump_interval);
 
 static bool wakeup_dumping_thread(const char*, const std::string&) {
     // We're modifying a flag, wake up dumping_thread to generate
@@ -912,22 +906,21 @@ static bool wakeup_dumping_thread(const char*, const std::string&) {
     return true;
 }
 
-const bool ALLOW_UNUSED dummy_bvar_dump_file = ::GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED dummy_bvar_dump_file = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_bvar_dump_file, wakeup_dumping_thread);
-const bool ALLOW_UNUSED dummy_bvar_dump_filter = ::GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED dummy_bvar_dump_filter = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_bvar_dump_include, wakeup_dumping_thread);
-const bool ALLOW_UNUSED dummy_bvar_dump_exclude = ::GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED dummy_bvar_dump_exclude = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_bvar_dump_exclude, wakeup_dumping_thread);
-const bool ALLOW_UNUSED dummy_bvar_dump_prefix = ::GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED dummy_bvar_dump_prefix = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_bvar_dump_prefix, wakeup_dumping_thread);
-const bool ALLOW_UNUSED dummy_bvar_dump_tabs = ::GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED dummy_bvar_dump_tabs = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_bvar_dump_tabs, wakeup_dumping_thread);
 
-const bool ALLOW_UNUSED dummy_mbvar_dump = ::GFLAGS_NS::RegisterFlagValidator(
-    &FLAGS_mbvar_dump, validate_bvar_dump);
-const bool ALLOW_UNUSED dummy_mbvar_dump_prefix = ::GFLAGS_NS::RegisterFlagValidator(
+BUTIL_VALIDATE_GFLAG(mbvar_dump, validate_bvar_dump);
+const bool ALLOW_UNUSED dummy_mbvar_dump_prefix = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_mbvar_dump_prefix, wakeup_dumping_thread);
-const bool ALLOW_UNUSED dump_mbvar_dump_file = ::GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED dump_mbvar_dump_file = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_mbvar_dump_file, wakeup_dumping_thread);
 
 static bool validate_mbvar_dump_format(const char*, const std::string& format) {
@@ -943,7 +936,7 @@ static bool validate_mbvar_dump_format(const char*, const std::string& format) {
     return true;
 }
 
-const bool ALLOW_UNUSED dummy_mbvar_dump_format = ::GFLAGS_NS::RegisterFlagValidator(
+const bool ALLOW_UNUSED dummy_mbvar_dump_format = GFLAGS_NAMESPACE::RegisterFlagValidator(
     &FLAGS_mbvar_dump_format, validate_mbvar_dump_format);
 
 void to_underscored_name(std::string* name, const butil::StringPiece& src) {
diff --git a/test/BUILD.bazel b/test/BUILD.bazel
index 3c4242da22..9817b45f10 100644
--- a/test/BUILD.bazel
+++ b/test/BUILD.bazel
@@ -29,7 +29,6 @@ COPTS = [
     "-fPIC",
     "-Wno-unused-parameter",
     "-fno-omit-frame-pointer",
-    "-DGFLAGS_NS=google",
     "-fno-access-control",
     "-DBAZEL_TEST=1",
     "-DBVAR_NOT_LINK_DEFAULT_VARIABLES",
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 11f1ad3b15..9f635e672c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -52,7 +52,7 @@ else()
     message(FATAL_ERROR "Googletest is not available")
 endif()
 
-set(CMAKE_CPP_FLAGS "${CMAKE_CPP_FLAGS} ${DEFINE_CLOCK_GETTIME} -DBRPC_WITH_GLOG=${WITH_GLOG_VAL} -DBRPC_WITH_RDMA=${WITH_RDMA_VAL} -DGFLAGS_NS=${GFLAGS_NS}")
+set(CMAKE_CPP_FLAGS "${CMAKE_CPP_FLAGS} ${DEFINE_CLOCK_GETTIME} -DBRPC_WITH_GLOG=${WITH_GLOG_VAL} -DBRPC_WITH_RDMA=${WITH_RDMA_VAL}")
 set(CMAKE_CPP_FLAGS "${CMAKE_CPP_FLAGS} -DBTHREAD_USE_FAST_PTHREAD_MUTEX -D__const__=__unused__ -D_GNU_SOURCE -DUSE_SYMBOLIZE -DNO_TCMALLOC -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -D__STDC_CONSTANT_MACROS -DUNIT_TEST -Dprivate=public -Dprotected=public -DBVAR_NOT_LINK_DEFAULT_VARIABLES -D__STRICT_ANSI__ -include ${PROJECT_SOURCE_DIR}/test/sstream_workaround.h")
 set(CMAKE_CXX_FLAGS "${CMAKE_CPP_FLAGS} -g -O2 -pipe -Wall -W -fPIC -fstrict-aliasing -Wno-invalid-offsetof -Wno-unused-parameter -fno-omit-frame-pointer")
 use_cxx11()
diff --git a/test/brpc_alpn_protocol_unittest.cpp b/test/brpc_alpn_protocol_unittest.cpp
index 7970db9af1..21aada70d6 100644
--- a/test/brpc_alpn_protocol_unittest.cpp
+++ b/test/brpc_alpn_protocol_unittest.cpp
@@ -32,7 +32,7 @@ DEFINE_string(listen_addr, "0.0.0.0:8011", "Server listen address.");
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);    
+    ::GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_block_pool_unittest.cpp b/test/brpc_block_pool_unittest.cpp
index d0bdd8e492..76e8c3258e 100644
--- a/test/brpc_block_pool_unittest.cpp
+++ b/test/brpc_block_pool_unittest.cpp
@@ -214,6 +214,6 @@ TEST_F(BlockPoolTest, dump_info) {
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
diff --git a/test/brpc_channel_unittest.cpp b/test/brpc_channel_unittest.cpp
index 7b98896b41..43d0ab7f1f 100644
--- a/test/brpc_channel_unittest.cpp
+++ b/test/brpc_channel_unittest.cpp
@@ -65,7 +65,7 @@ int main(int argc, char* argv[]) {
     brpc::FLAGS_idle_timeout_second = 0;
     brpc::FLAGS_max_connection_pool_size = 0;
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_circuit_breaker_unittest.cpp b/test/brpc_circuit_breaker_unittest.cpp
index e8f55153f3..607fede9ea 100644
--- a/test/brpc_circuit_breaker_unittest.cpp
+++ b/test/brpc_circuit_breaker_unittest.cpp
@@ -67,7 +67,7 @@ int main(int argc, char* argv[]) {
     brpc::FLAGS_circuit_breaker_max_isolation_duration_ms = kMaxIsolationDurationMs;
     brpc::FLAGS_circuit_breaker_half_open_window_size = kHalfWindowSize;
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_coroutine_unittest.cpp b/test/brpc_coroutine_unittest.cpp
index b89c1408cb..1df2c3a0e4 100644
--- a/test/brpc_coroutine_unittest.cpp
+++ b/test/brpc_coroutine_unittest.cpp
@@ -24,7 +24,7 @@
 int main(int argc, char* argv[]) {
 #ifdef BRPC_ENABLE_COROUTINE
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 #else
     printf("bRPC coroutine is not enabled, please add -std=c++20 to compile options\n");
diff --git a/test/brpc_esp_protocol_unittest.cpp b/test/brpc_esp_protocol_unittest.cpp
index 4db1943cc9..d4cab7c47d 100644
--- a/test/brpc_esp_protocol_unittest.cpp
+++ b/test/brpc_esp_protocol_unittest.cpp
@@ -37,7 +37,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_grpc_protocol_unittest.cpp b/test/brpc_grpc_protocol_unittest.cpp
index 4818b319b5..f170639d17 100644
--- a/test/brpc_grpc_protocol_unittest.cpp
+++ b/test/brpc_grpc_protocol_unittest.cpp
@@ -27,12 +27,12 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
-    if (GFLAGS_NS::SetCommandLineOption("http_body_compress_threshold", "0").empty()) {
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
+    if (GFLAGS_NAMESPACE::SetCommandLineOption("http_body_compress_threshold", "0").empty()) {
         std::cerr << "Fail to set -crash_on_fatal_log" << std::endl;
         return -1;
     }
-    if (GFLAGS_NS::SetCommandLineOption("crash_on_fatal_log", "true").empty()) {
+    if (GFLAGS_NAMESPACE::SetCommandLineOption("crash_on_fatal_log", "true").empty()) {
         std::cerr << "Fail to set -crash_on_fatal_log" << std::endl;
         return -1;
     }
diff --git a/test/brpc_http_message_unittest.cpp b/test/brpc_http_message_unittest.cpp
index 0d5a979a38..d6f206cd07 100644
--- a/test/brpc_http_message_unittest.cpp
+++ b/test/brpc_http_message_unittest.cpp
@@ -32,7 +32,7 @@ DECLARE_bool(allow_http_1_1_request_without_host);
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     brpc::FLAGS_allow_http_1_1_request_without_host = true;
     return RUN_ALL_TESTS();
 }
@@ -77,7 +77,7 @@ TEST(HttpMessageTest, http_method) {
 }
 
 TEST(HttpMessageTest, eof) {
-    GFLAGS_NS::SetCommandLineOption("verbose", "100");
+    GFLAGS_NAMESPACE::SetCommandLineOption("verbose", "100");
     const char* http_request = 
         "GET /CloudApiControl/HttpServer/telematics/v3/weather?location=%E6%B5%B7%E5%8D%97%E7%9C%81%E7%9B%B4%E8%BE%96%E5%8E%BF%E7%BA%A7%E8%A1%8C%E6%94%BF%E5%8D%95%E4%BD%8D&output=json&ak=0l3FSP6qA0WbOzGRaafbmczS HTTP/1.1\r\n"
         "X-Host: api.map.baidu.com\r\n"
diff --git a/test/brpc_http_rpc_protocol_unittest.cpp b/test/brpc_http_rpc_protocol_unittest.cpp
index f4bdec955f..d2dcf972c6 100644
--- a/test/brpc_http_rpc_protocol_unittest.cpp
+++ b/test/brpc_http_rpc_protocol_unittest.cpp
@@ -65,12 +65,12 @@ extern bvar::CollectorSpeedLimit g_rpc_dump_sl;
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
-    if (GFLAGS_NS::SetCommandLineOption("socket_max_unwritten_bytes", "2000000").empty()) {
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
+    if (GFLAGS_NAMESPACE::SetCommandLineOption("socket_max_unwritten_bytes", "2000000").empty()) {
         std::cerr << "Fail to set -socket_max_unwritten_bytes" << std::endl;
         return -1;
     }
-    if (GFLAGS_NS::SetCommandLineOption("crash_on_fatal_log", "true").empty()) {
+    if (GFLAGS_NAMESPACE::SetCommandLineOption("crash_on_fatal_log", "true").empty()) {
         std::cerr << "Fail to set -crash_on_fatal_log" << std::endl;
         return -1;
     }
diff --git a/test/brpc_hulu_pbrpc_protocol_unittest.cpp b/test/brpc_hulu_pbrpc_protocol_unittest.cpp
index 7830b3038f..7c971dc2a8 100644
--- a/test/brpc_hulu_pbrpc_protocol_unittest.cpp
+++ b/test/brpc_hulu_pbrpc_protocol_unittest.cpp
@@ -39,7 +39,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_interceptor_unittest.cpp b/test/brpc_interceptor_unittest.cpp
index b786f1039d..6238c3fefd 100644
--- a/test/brpc_interceptor_unittest.cpp
+++ b/test/brpc_interceptor_unittest.cpp
@@ -32,7 +32,7 @@ DECLARE_bool(use_http_error_code);
 
 int main(int argc, char* argv[]) {
     ::testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_load_balancer_unittest.cpp b/test/brpc_load_balancer_unittest.cpp
index 14b0131cf4..509456e71c 100644
--- a/test/brpc_load_balancer_unittest.cpp
+++ b/test/brpc_load_balancer_unittest.cpp
@@ -1191,11 +1191,11 @@ TEST_F(LoadBalancerTest, invalid_lb_params) {
 }
 
 TEST_F(LoadBalancerTest, revived_from_all_failed_intergrated) {
-    GFLAGS_NS::SetCommandLineOption("circuit_breaker_short_window_size", "20");
-    GFLAGS_NS::SetCommandLineOption("circuit_breaker_short_window_error_percent", "30");
+    GFLAGS_NAMESPACE::SetCommandLineOption("circuit_breaker_short_window_size", "20");
+    GFLAGS_NAMESPACE::SetCommandLineOption("circuit_breaker_short_window_error_percent", "30");
     // Those two lines force the interval of first hc to 3s
-    GFLAGS_NS::SetCommandLineOption("circuit_breaker_max_isolation_duration_ms", "3000");
-    GFLAGS_NS::SetCommandLineOption("circuit_breaker_min_isolation_duration_ms", "3000");
+    GFLAGS_NAMESPACE::SetCommandLineOption("circuit_breaker_max_isolation_duration_ms", "3000");
+    GFLAGS_NAMESPACE::SetCommandLineOption("circuit_breaker_min_isolation_duration_ms", "3000");
 
     const char* lb_algo[] = { "random:min_working_instances=2 hold_seconds=2",
                               "rr:min_working_instances=2 hold_seconds=2" };
diff --git a/test/brpc_mongo_protocol_unittest.cpp b/test/brpc_mongo_protocol_unittest.cpp
index 17c3dee4d2..64e3bf394c 100644
--- a/test/brpc_mongo_protocol_unittest.cpp
+++ b/test/brpc_mongo_protocol_unittest.cpp
@@ -39,7 +39,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_public_pbrpc_protocol_unittest.cpp b/test/brpc_public_pbrpc_protocol_unittest.cpp
index 82c9fc52d9..e92f5ed917 100644
--- a/test/brpc_public_pbrpc_protocol_unittest.cpp
+++ b/test/brpc_public_pbrpc_protocol_unittest.cpp
@@ -38,7 +38,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_rdma_unittest.cpp b/test/brpc_rdma_unittest.cpp
index 6cf3eddfea..26a8236116 100644
--- a/test/brpc_rdma_unittest.cpp
+++ b/test/brpc_rdma_unittest.cpp
@@ -1955,7 +1955,7 @@ TEST_F(RdmaTest, try_memory_pool_empty) {
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 #if BRPC_WITH_RDMA
     rdma::FLAGS_rdma_trace_verbose = true;
     rdma::FLAGS_rdma_memory_pool_max_regions = 2;
diff --git a/test/brpc_rtmp_unittest.cpp b/test/brpc_rtmp_unittest.cpp
index 10cd842ed7..5853f7778d 100644
--- a/test/brpc_rtmp_unittest.cpp
+++ b/test/brpc_rtmp_unittest.cpp
@@ -37,7 +37,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_server_unittest.cpp b/test/brpc_server_unittest.cpp
index 70f7ed3654..676f16626d 100644
--- a/test/brpc_server_unittest.cpp
+++ b/test/brpc_server_unittest.cpp
@@ -60,7 +60,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_socket_unittest.cpp b/test/brpc_socket_unittest.cpp
index 3f9b88ad8d..4852ab7e74 100644
--- a/test/brpc_socket_unittest.cpp
+++ b/test/brpc_socket_unittest.cpp
@@ -59,13 +59,14 @@ DECLARE_bool(socket_keepalive);
 DECLARE_int32(socket_keepalive_idle_s);
 DECLARE_int32(socket_keepalive_interval_s);
 DECLARE_int32(socket_keepalive_count);
+DECLARE_int32(socket_tcp_user_timeout_ms);
 }
 
 void EchoProcessHuluRequest(brpc::InputMessageBase* msg_base);
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     brpc::Protocol dummy_protocol = 
                              { brpc::policy::ParseHuluMessage,
                                brpc::SerializeRequestDefault, 
@@ -590,8 +591,8 @@ class HealthCheckTestServiceImpl : public test::HealthCheckTestService {
 
 TEST_F(SocketTest, app_level_health_check) {
     int old_health_check_interval = brpc::FLAGS_health_check_interval;
-    GFLAGS_NS::SetCommandLineOption("health_check_path", "/HealthCheckTestService");
-    GFLAGS_NS::SetCommandLineOption("health_check_interval", "1");
+    GFLAGS_NAMESPACE::SetCommandLineOption("health_check_path", "/HealthCheckTestService");
+    GFLAGS_NAMESPACE::SetCommandLineOption("health_check_interval", "1");
 
     butil::EndPoint point(butil::IP_ANY, 7777);
     brpc::ChannelOptions options;
@@ -643,10 +644,10 @@ TEST_F(SocketTest, app_level_health_check) {
         ASSERT_GT(cntl.response_attachment().size(), (size_t)0);
     }
 
-    GFLAGS_NS::SetCommandLineOption("health_check_path", "");
+    GFLAGS_NAMESPACE::SetCommandLineOption("health_check_path", "");
     char hc_buf[8];
     snprintf(hc_buf, sizeof(hc_buf), "%d", old_health_check_interval);
-    GFLAGS_NS::SetCommandLineOption("health_check_interval", hc_buf);
+    GFLAGS_NAMESPACE::SetCommandLineOption("health_check_interval", hc_buf);
 }
 
 TEST_F(SocketTest, health_check) {
@@ -1113,16 +1114,15 @@ TEST_F(SocketTest, keepalive) {
     int default_keepalive_count = 0;
     {
         butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
-        GetKeepaliveValue(sockfd,
-                          default_keepalive,
-                          default_keepalive_idle,
-                          default_keepalive_interval,
-                          default_keepalive_count);
+        ASSERT_GT(sockfd, 0);
+        GetKeepaliveValue(sockfd, default_keepalive, default_keepalive_idle,
+                          default_keepalive_interval, default_keepalive_count);
     }
 
     // Disable keepalive.
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         brpc::SocketId id;
@@ -1130,7 +1130,6 @@ TEST_F(SocketTest, keepalive) {
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
         CheckNoKeepalive(ptr->fd());
-        sockfd.release();
     }
 
     int keepalive_idle = 1;
@@ -1138,7 +1137,8 @@ TEST_F(SocketTest, keepalive) {
     int keepalive_count = 2;
     // Enable keepalive.
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
@@ -1146,17 +1146,14 @@ TEST_F(SocketTest, keepalive) {
         ASSERT_EQ(0, brpc::Socket::Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       default_keepalive_idle,
-                       default_keepalive_interval,
-                       default_keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, default_keepalive_idle,
+                       default_keepalive_interval, default_keepalive_count);
     }
 
     // Enable keepalive and set keepalive idle.
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
@@ -1166,17 +1163,15 @@ TEST_F(SocketTest, keepalive) {
         ASSERT_EQ(0, brpc::Socket::Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       keepalive_idle,
+        CheckKeepalive(ptr->fd(), true, keepalive_idle,
                        default_keepalive_interval,
                        default_keepalive_count);
-        sockfd.release();
     }
 
     // Enable keepalive and set keepalive interval.
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
@@ -1186,56 +1181,42 @@ TEST_F(SocketTest, keepalive) {
         ASSERT_EQ(0, brpc::Socket::Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       default_keepalive_idle,
-                       keepalive_interval,
-                       default_keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, default_keepalive_idle,
+                       keepalive_interval, default_keepalive_count);
     }
 
     // Enable keepalive and set keepalive count.
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
-        options.keepalive_options->keepalive_count
-            = keepalive_count;
+        options.keepalive_options->keepalive_count = keepalive_count;
         brpc::SocketId id;
         ASSERT_EQ(0, brpc::Socket::Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       default_keepalive_idle,
-                       default_keepalive_interval,
-                       keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, default_keepalive_idle,
+                       default_keepalive_interval, keepalive_count);
     }
 
     // Enable keepalive and set keepalive idle, interval, count.
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
-        options.keepalive_options->keepalive_idle_s
-            = keepalive_idle;
-        options.keepalive_options->keepalive_interval_s
-            = keepalive_interval;
-        options.keepalive_options->keepalive_count
-            = keepalive_count;
+        options.keepalive_options->keepalive_idle_s = keepalive_idle;
+        options.keepalive_options->keepalive_interval_s = keepalive_interval;
+        options.keepalive_options->keepalive_count = keepalive_count;
         brpc::SocketId id;
         ASSERT_EQ(0, brpc::Socket::Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       keepalive_idle,
-                       keepalive_interval,
-                       keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, keepalive_idle,
+                       keepalive_interval, keepalive_count);
     }
 }
 
@@ -1246,101 +1227,83 @@ TEST_F(SocketTest, keepalive_input_message) {
     int default_keepalive_count = 0;
     {
         butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
-        GetKeepaliveValue(sockfd,
-                          default_keepalive,
-                          default_keepalive_idle,
-                          default_keepalive_interval,
-                          default_keepalive_count);
+        ASSERT_GT(sockfd, 0);
+        GetKeepaliveValue(sockfd, default_keepalive, default_keepalive_idle,
+                          default_keepalive_interval, default_keepalive_count);
     }
 
     // Disable keepalive.
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
         CheckNoKeepalive(ptr->fd());
-        sockfd.release();
     }
 
     // Enable keepalive.
     brpc::FLAGS_socket_keepalive = true;
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       default_keepalive_idle,
-                       default_keepalive_interval,
-                       default_keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, default_keepalive_idle,
+                       default_keepalive_interval, default_keepalive_count);
     }
 
     // Enable keepalive and set keepalive idle.
     brpc::FLAGS_socket_keepalive_idle_s = 10;
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       brpc::FLAGS_socket_keepalive_idle_s,
-                       default_keepalive_interval,
-                       default_keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, brpc::FLAGS_socket_keepalive_idle_s,
+                       default_keepalive_interval, default_keepalive_count);
     }
 
     // Enable keepalive and set keepalive idle, interval.
     brpc::FLAGS_socket_keepalive_interval_s = 10;
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       brpc::FLAGS_socket_keepalive_idle_s,
-                       brpc::FLAGS_socket_keepalive_interval_s,
-                       default_keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, brpc::FLAGS_socket_keepalive_idle_s,
+                       brpc::FLAGS_socket_keepalive_interval_s, default_keepalive_count);
     }
 
     // Enable keepalive and set keepalive idle, interval, count.
     brpc::FLAGS_socket_keepalive_count = 10;
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       brpc::FLAGS_socket_keepalive_idle_s,
+        CheckKeepalive(ptr->fd(), true, brpc::FLAGS_socket_keepalive_idle_s,
                        brpc::FLAGS_socket_keepalive_interval_s,
                        brpc::FLAGS_socket_keepalive_count);
-        sockfd.release();
     }
 
     // Options of keepalive set by user have priority over Gflags.
@@ -1348,90 +1311,132 @@ TEST_F(SocketTest, keepalive_input_message) {
     int keepalive_interval = 2;
     int keepalive_count = 2;
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
-        options.keepalive_options->keepalive_idle_s
-            = keepalive_idle;
+        options.keepalive_options->keepalive_idle_s = keepalive_idle;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       keepalive_idle,
+        CheckKeepalive(ptr->fd(), true, keepalive_idle,
                        brpc::FLAGS_socket_keepalive_interval_s,
                        brpc::FLAGS_socket_keepalive_count);
-        sockfd.release();
     }
 
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
-        options.keepalive_options->keepalive_interval_s
-            = keepalive_interval;
+        options.keepalive_options->keepalive_interval_s = keepalive_interval;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       brpc::FLAGS_socket_keepalive_idle_s,
-                       keepalive_interval,
-                       brpc::FLAGS_socket_keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, brpc::FLAGS_socket_keepalive_idle_s,
+                       keepalive_interval, brpc::FLAGS_socket_keepalive_count);
     }
 
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
-        options.keepalive_options->keepalive_count
-            = keepalive_count;
+        options.keepalive_options->keepalive_count = keepalive_count;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       brpc::FLAGS_socket_keepalive_idle_s,
-                       brpc::FLAGS_socket_keepalive_interval_s,
-                       keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, brpc::FLAGS_socket_keepalive_idle_s,
+                       brpc::FLAGS_socket_keepalive_interval_s, keepalive_count);
     }
 
     {
-        butil::fd_guard sockfd(socket(AF_INET, SOCK_STREAM, 0));
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
         brpc::SocketOptions options;
         options.fd = sockfd;
         options.keepalive_options = std::make_shared<brpc::SocketKeepaliveOptions>();
-        options.keepalive_options->keepalive_idle_s
-            = keepalive_idle;
-        options.keepalive_options->keepalive_interval_s
-            = keepalive_interval;
-        options.keepalive_options->keepalive_count
-            = keepalive_count;
+        options.keepalive_options->keepalive_idle_s = keepalive_idle;
+        options.keepalive_options->keepalive_interval_s = keepalive_interval;
+        options.keepalive_options->keepalive_count = keepalive_count;
         brpc::SocketId id;
-        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()
-            ->Create(options, &id));
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
         brpc::SocketUniquePtr ptr;
         ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
-        CheckKeepalive(ptr->fd(),
-                       true,
-                       keepalive_idle,
-                       keepalive_interval,
-                       keepalive_count);
-        sockfd.release();
+        CheckKeepalive(ptr->fd(), true, keepalive_idle,
+                       keepalive_interval, keepalive_count);
     }
 }
 
+#if defined(OS_LINUX)
+void CheckTCPUserTimeout(int fd, int expect_tcp_user_timeout) {
+    int tcp_user_timeout = 0;
+    socklen_t len = sizeof(tcp_user_timeout);
+    ASSERT_EQ(0, getsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT, &tcp_user_timeout, &len) );
+    ASSERT_EQ(tcp_user_timeout, expect_tcp_user_timeout);
+}
+
+TEST_F(SocketTest, tcp_user_timeout) {
+    {
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
+        brpc::SocketOptions options;
+        options.fd = sockfd;
+        brpc::SocketId id;
+        ASSERT_EQ(0, brpc::Socket::Create(options, &id));
+        brpc::SocketUniquePtr ptr;
+        ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
+        CheckTCPUserTimeout(ptr->fd(), 0);
+    }
+
+    {
+        int tcp_user_timeout_ms = 1000;
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
+        brpc::SocketOptions options;
+        options.fd = sockfd;
+        options.tcp_user_timeout_ms = tcp_user_timeout_ms;
+        brpc::SocketId id;
+        ASSERT_EQ(0, brpc::Socket::Create(options, &id));
+        brpc::SocketUniquePtr ptr;
+        ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
+        CheckTCPUserTimeout(ptr->fd(), tcp_user_timeout_ms);
+    }
+
+    brpc::FLAGS_socket_tcp_user_timeout_ms = 2000;
+    {
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
+        brpc::SocketOptions options;
+        options.fd = sockfd;
+        brpc::SocketId id;
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
+        brpc::SocketUniquePtr ptr;
+        ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
+        CheckTCPUserTimeout(ptr->fd(), brpc::FLAGS_socket_tcp_user_timeout_ms);
+    }
+    {
+        int tcp_user_timeout_ms = 3000;
+        int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        ASSERT_GT(sockfd, 0);
+        brpc::SocketOptions options;
+        options.fd = sockfd;
+        options.tcp_user_timeout_ms = tcp_user_timeout_ms;
+        brpc::SocketId id;
+        ASSERT_EQ(0, brpc::get_or_new_client_side_messenger()->Create(options, &id));
+        brpc::SocketUniquePtr ptr;
+        ASSERT_EQ(0, brpc::Socket::Address(id, &ptr));
+        CheckTCPUserTimeout(ptr->fd(), tcp_user_timeout_ms);
+    }
+}
+#endif
+
 int HandleSocketSuccessWrite(bthread_id_t id, void* data, int error_code,
     const std::string& error_text) {
     auto success_count = static_cast<size_t*>(data);
diff --git a/test/brpc_sofa_pbrpc_protocol_unittest.cpp b/test/brpc_sofa_pbrpc_protocol_unittest.cpp
index c875f7bd4b..4cf91b4fd4 100644
--- a/test/brpc_sofa_pbrpc_protocol_unittest.cpp
+++ b/test/brpc_sofa_pbrpc_protocol_unittest.cpp
@@ -38,7 +38,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/brpc_ssl_unittest.cpp b/test/brpc_ssl_unittest.cpp
index 3c64ba765b..a7ef1c209e 100644
--- a/test/brpc_ssl_unittest.cpp
+++ b/test/brpc_ssl_unittest.cpp
@@ -45,7 +45,7 @@ void ExtractHostnames(X509* x, std::vector<std::string>* hostnames);
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     brpc::GlobalInitializeOrDie();
     return RUN_ALL_TESTS();
 }
diff --git a/test/bthread_butex_multi_tag_unittest.cpp b/test/bthread_butex_multi_tag_unittest.cpp
index 98057d4a8e..e41fefddaf 100644
--- a/test/bthread_butex_multi_tag_unittest.cpp
+++ b/test/bthread_butex_multi_tag_unittest.cpp
@@ -27,7 +27,7 @@ DECLARE_int32(task_group_ntags);
 int main(int argc, char* argv[]) {
     FLAGS_task_group_ntags = 3;
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/bthread_key_unittest.cpp b/test/bthread_key_unittest.cpp
index a7f11e7653..4319fb4180 100644
--- a/test/bthread_key_unittest.cpp
+++ b/test/bthread_key_unittest.cpp
@@ -40,7 +40,7 @@ int main(int argc, char* argv[]) {
     bthread::FLAGS_key_table_list_size = 20;
     bthread::FLAGS_borrow_from_globle_size = 20;
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
 
diff --git a/test/bthread_setconcurrency_unittest.cpp b/test/bthread_setconcurrency_unittest.cpp
index aa1d674c22..4d269b642b 100644
--- a/test/bthread_setconcurrency_unittest.cpp
+++ b/test/bthread_setconcurrency_unittest.cpp
@@ -140,13 +140,13 @@ void* add_concurrency_proc(void*) {
 bool set_min_concurrency(int num) {
     std::stringstream ss;
     ss << num;
-    std::string ret = GFLAGS_NS::SetCommandLineOption("bthread_min_concurrency", ss.str().c_str());
+    std::string ret = GFLAGS_NAMESPACE::SetCommandLineOption("bthread_min_concurrency", ss.str().c_str());
     return !ret.empty();
 }
 
 int get_min_concurrency() {
     std::string ret;
-    GFLAGS_NS::GetCommandLineOption("bthread_min_concurrency", &ret);
+    GFLAGS_NAMESPACE::GetCommandLineOption("bthread_min_concurrency", &ret);
     return atoi(ret.c_str());
 }
 
@@ -194,7 +194,7 @@ TEST(BthreadTest, min_concurrency) {
 int current_tag(int tag) {
     std::stringstream ss;
     ss << tag;
-    std::string ret = GFLAGS_NS::SetCommandLineOption("bthread_current_tag", ss.str().c_str());
+    std::string ret = GFLAGS_NAMESPACE::SetCommandLineOption("bthread_current_tag", ss.str().c_str());
     return !(ret.empty());
 }
 
@@ -208,7 +208,7 @@ int concurrency_by_tag(int num) {
     std::stringstream ss;
     ss << num;
     std::string ret =
-        GFLAGS_NS::SetCommandLineOption("bthread_concurrency_by_tag", ss.str().c_str());
+        GFLAGS_NAMESPACE::SetCommandLineOption("bthread_concurrency_by_tag", ss.str().c_str());
     return !(ret.empty());
 }
 
diff --git a/test/bthread_unittest.cpp b/test/bthread_unittest.cpp
index d160523403..0286db9904 100644
--- a/test/bthread_unittest.cpp
+++ b/test/bthread_unittest.cpp
@@ -27,7 +27,7 @@
 
 int main(int argc, char* argv[]) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     int rc = RUN_ALL_TESTS();
     return rc;
 }
diff --git a/test/butil_unittest_main.cpp b/test/butil_unittest_main.cpp
index 96277e6423..c7c6965c1e 100644
--- a/test/butil_unittest_main.cpp
+++ b/test/butil_unittest_main.cpp
@@ -27,8 +27,8 @@ DEFINE_bool(disable_coredump, false, "Never core dump");
 int main(int argc, char** argv) {
     butil::AtExitManager at_exit;
     testing::InitGoogleTest(&argc, argv);
-    
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     if (FLAGS_disable_coredump) {
         rlimit core_limit;
         core_limit.rlim_cur = 0;
@@ -36,7 +36,7 @@ int main(int argc, char** argv) {
         setrlimit(RLIMIT_CORE, &core_limit);
     }
 #if !BRPC_WITH_GLOG
-    CHECK(!GFLAGS_NS::SetCommandLineOption("crash_on_fatal_log", "true").empty());
+    CHECK(!GFLAGS_NAMESPACE::SetCommandLineOption("crash_on_fatal_log", "true").empty());
 #endif
     return RUN_ALL_TESTS();
 }
diff --git a/test/bvar_file_dumper_unittest.cpp b/test/bvar_file_dumper_unittest.cpp
index 9e80cef10d..9a6bb0a095 100644
--- a/test/bvar_file_dumper_unittest.cpp
+++ b/test/bvar_file_dumper_unittest.cpp
@@ -34,7 +34,7 @@ TEST_F(FileDumperTest, filters) {
     bvar::Adder<int> a3("a_error");
     bvar::Adder<int> a4("process_*");
     bvar::Adder<int> a5("default");
-    GFLAGS_NS::SetCommandLineOption("bvar_dump_interval", "1");
-    GFLAGS_NS::SetCommandLineOption("bvar_dump", "true");
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_dump_interval", "1");
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_dump", "true");
     sleep(2);
 }
diff --git a/test/bvar_multi_dimension_unittest.cpp b/test/bvar_multi_dimension_unittest.cpp
index 974090d0a6..8d0e479d0d 100644
--- a/test/bvar_multi_dimension_unittest.cpp
+++ b/test/bvar_multi_dimension_unittest.cpp
@@ -401,17 +401,17 @@ TEST_F(MultiDimensionTest, mlatencyrecorder) {
     std::string old_bvar_latency_p2;
     std::string old_bvar_latency_p3;
 
-    GFLAGS_NS::GetCommandLineOption("bvar_dump_interval", &old_bvar_dump_interval);
-    GFLAGS_NS::GetCommandLineOption("mbvar_dump", &old_mbvar_dump);
-    GFLAGS_NS::GetCommandLineOption("bvar_latency_p1", &old_bvar_latency_p1);
-    GFLAGS_NS::GetCommandLineOption("bvar_latency_p2", &old_bvar_latency_p2);
-    GFLAGS_NS::GetCommandLineOption("bvar_latency_p3", &old_bvar_latency_p3);
-
-    GFLAGS_NS::SetCommandLineOption("bvar_dump_interval", "1");
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump", "true");
-    GFLAGS_NS::SetCommandLineOption("bvar_latency_p1", "60");
-    GFLAGS_NS::SetCommandLineOption("bvar_latency_p2", "70");
-    GFLAGS_NS::SetCommandLineOption("bvar_latency_p3", "80");
+    GFLAGS_NAMESPACE::GetCommandLineOption("bvar_dump_interval", &old_bvar_dump_interval);
+    GFLAGS_NAMESPACE::GetCommandLineOption("mbvar_dump", &old_mbvar_dump);
+    GFLAGS_NAMESPACE::GetCommandLineOption("bvar_latency_p1", &old_bvar_latency_p1);
+    GFLAGS_NAMESPACE::GetCommandLineOption("bvar_latency_p2", &old_bvar_latency_p2);
+    GFLAGS_NAMESPACE::GetCommandLineOption("bvar_latency_p3", &old_bvar_latency_p3);
+
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_dump_interval", "1");
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump", "true");
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_latency_p1", "60");
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_latency_p2", "70");
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_latency_p3", "80");
 
     bvar::MultiDimension<bvar::LatencyRecorder> my_mlatencyrecorder("client_request_count_mlatencyrecorder", labels);
     std::list<std::string> labels_value = {"tc", "get", "200"};
@@ -424,11 +424,11 @@ TEST_F(MultiDimensionTest, mlatencyrecorder) {
     ASSERT_LE(7, my_latencyrecorder->qps());
     ASSERT_EQ(7, my_latencyrecorder->count());
 
-    GFLAGS_NS::SetCommandLineOption("bvar_dump_interval", old_bvar_dump_interval.c_str());
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump", old_mbvar_dump.c_str());
-    GFLAGS_NS::SetCommandLineOption("bvar_latency_p1", old_bvar_latency_p1.c_str());
-    GFLAGS_NS::SetCommandLineOption("bvar_latency_p2", old_bvar_latency_p2.c_str());
-    GFLAGS_NS::SetCommandLineOption("bvar_latency_p3", old_bvar_latency_p3.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_dump_interval", old_bvar_dump_interval.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump", old_mbvar_dump.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_latency_p1", old_bvar_latency_p1.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_latency_p2", old_bvar_latency_p2.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_latency_p3", old_bvar_latency_p3.c_str());
 }
 
 TEST_F(MultiDimensionTest, mstatus) {
diff --git a/test/bvar_mvariable_unittest.cpp b/test/bvar_mvariable_unittest.cpp
index 8e783317c3..5ab171c4d8 100644
--- a/test/bvar_mvariable_unittest.cpp
+++ b/test/bvar_mvariable_unittest.cpp
@@ -158,15 +158,15 @@ TEST_F(MVariableTest, dump) {
     std::string old_mbvar_dump_prefix;
     std::string old_mbvar_dump_format;
 
-    GFLAGS_NS::GetCommandLineOption("bvar_dump_interval", &old_bvar_dump_interval);
-    GFLAGS_NS::GetCommandLineOption("mbvar_dump", &old_mbvar_dump);
-    GFLAGS_NS::GetCommandLineOption("mbvar_dump_prefix", &old_mbvar_dump_prefix);
-    GFLAGS_NS::GetCommandLineOption("mbvar_dump_format", &old_mbvar_dump_format);
+    GFLAGS_NAMESPACE::GetCommandLineOption("bvar_dump_interval", &old_bvar_dump_interval);
+    GFLAGS_NAMESPACE::GetCommandLineOption("mbvar_dump", &old_mbvar_dump);
+    GFLAGS_NAMESPACE::GetCommandLineOption("mbvar_dump_prefix", &old_mbvar_dump_prefix);
+    GFLAGS_NAMESPACE::GetCommandLineOption("mbvar_dump_format", &old_mbvar_dump_format);
 
-    GFLAGS_NS::SetCommandLineOption("bvar_dump_interval", "1");
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump", "true");
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump_prefix", "my_mdump_prefix");
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump_format", "common");
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_dump_interval", "1");
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump", "true");
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump_prefix", "my_mdump_prefix");
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump_format", "common");
 
     bvar::MultiDimension<bvar::Adder<int> > my_madder("dump_adder", labels);
     std::list<std::string> labels_value1 {"gz", "post", "200"};
@@ -218,10 +218,10 @@ TEST_F(MVariableTest, dump) {
     *my_latencyrecorder1 << 3 << 6 << 9;
     sleep(2);
     
-    GFLAGS_NS::SetCommandLineOption("bvar_dump_interval", old_bvar_dump_interval.c_str());
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump", old_mbvar_dump.c_str());
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump_prefix", old_mbvar_dump_prefix.c_str());
-    GFLAGS_NS::SetCommandLineOption("mbvar_dump_format", old_mbvar_dump_format.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("bvar_dump_interval", old_bvar_dump_interval.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump", old_mbvar_dump.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump_prefix", old_mbvar_dump_prefix.c_str());
+    GFLAGS_NAMESPACE::SetCommandLineOption("mbvar_dump_format", old_mbvar_dump_format.c_str());
 }
 
 TEST_F(MVariableTest, test_describe_exposed) {
diff --git a/test/bvar_variable_unittest.cpp b/test/bvar_variable_unittest.cpp
index 263a1ede3f..7450da6910 100644
--- a/test/bvar_variable_unittest.cpp
+++ b/test/bvar_variable_unittest.cpp
@@ -396,6 +396,6 @@ TEST_F(VariableTest, recursive_mutex) {
 
 int main(int argc, char** argv) {
     testing::InitGoogleTest(&argc, argv);
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     return RUN_ALL_TESTS();
 }
diff --git a/test/logging_unittest.cc b/test/logging_unittest.cc
index 018b2aa535..a431e01b60 100644
--- a/test/logging_unittest.cc
+++ b/test/logging_unittest.cc
@@ -59,8 +59,8 @@ class LoggingTest : public testing::Test {
         ::logging::FLAGS_crash_on_fatal_log = _old_crash_on_fatal_log;
         if (::logging::FLAGS_v != 0) {
             // Clear -verbose to avoid affecting other tests.
-            ASSERT_FALSE(GFLAGS_NS::SetCommandLineOption("v", "0").empty());
-            ASSERT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule", "").empty());
+            ASSERT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("v", "0").empty());
+            ASSERT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule", "").empty());
         }
     }
 private:
@@ -218,11 +218,11 @@ TEST_F(LoggingTest, log_at) {
 TEST_F(LoggingTest, vlog_sanity) {
     ::logging::FLAGS_crash_on_fatal_log = false;
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("v", "1").empty());
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("v", "1").empty());
     
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule",
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule",
                                                "logging_unittest=1").empty());
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule",
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule",
                                                "logging_UNITTEST=2").empty());
 
     for (int i = 0; i < 10; ++i) {
@@ -238,7 +238,7 @@ TEST_F(LoggingTest, vlog_sanity) {
     VLOG_NE(0) << "always on";
     EXPECT_EQ("always on", LOG_STREAM(INFO).content_str());
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule",
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule",
                                               "logging_unittest=0").empty());
     for (int i = 0; i < 10; ++i) {
         VLOG_NE(i) << "vlog " << i;
@@ -246,7 +246,7 @@ TEST_F(LoggingTest, vlog_sanity) {
     EXPECT_EQ("", LOG_STREAM(VERBOSE).content_str());
     EXPECT_EQ("vlog 0", LOG_STREAM(INFO).content_str());
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule",
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule",
                      "logging_unittest=0,logging_unittest=1").empty());
     for (int i = 0; i < 10; ++i) {
         VLOG_NE(i) << "vlog " << i;
@@ -254,7 +254,7 @@ TEST_F(LoggingTest, vlog_sanity) {
     EXPECT_EQ("vlog 1", LOG_STREAM(VERBOSE).content_str());
     EXPECT_EQ("vlog 0", LOG_STREAM(INFO).content_str());
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule",
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule",
                      "logging_unittest=1,logging_unittest=0").empty());
     for (int i = 0; i < 10; ++i) {
         VLOG_NE(i) << "vlog " << i;
@@ -262,14 +262,14 @@ TEST_F(LoggingTest, vlog_sanity) {
     EXPECT_EQ("", LOG_STREAM(VERBOSE).content_str());
     EXPECT_EQ("vlog 0", LOG_STREAM(INFO).content_str());
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule", "").empty());
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule", "").empty());
     for (int i = 0; i < 10; ++i) {
         VLOG_NE(i) << "vlog " << i;
     }
     EXPECT_EQ("vlog 1", LOG_STREAM(VERBOSE).content_str());
     EXPECT_EQ("vlog 0", LOG_STREAM(INFO).content_str());
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule",
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule",
                                                "logg?ng_*=2").empty());
     for (int i = 0; i < 10; ++i) {
         VLOG_NE(i) << "vlog " << i;
@@ -277,7 +277,7 @@ TEST_F(LoggingTest, vlog_sanity) {
     EXPECT_EQ("vlog 1vlog 2", LOG_STREAM(VERBOSE).content_str());
     EXPECT_EQ("vlog 0", LOG_STREAM(INFO).content_str());
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule",
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule",
         "foo=3,logging_unittest=3, logg?ng_*=2 , logging_*=1 ").empty());
     for (int i = 0; i < 10; ++i) {
         VLOG_NE(i) << "vlog " << i;
@@ -290,7 +290,7 @@ TEST_F(LoggingTest, vlog_sanity) {
     }
     EXPECT_EQ("vlog 1vlog 3", LOG_STREAM(VERBOSE).content_str());
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption(
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption(
                      "vmodule",
                      "foo/bar0/0=2,foo/bar/1=3, 2=4, foo/*/3=5, */ba?/4=6,"
                      "/5=7,/foo/bar/6=8,foo2/bar/7=9,foo/bar/8=9").empty());
@@ -373,8 +373,8 @@ TEST_F(LoggingTest, debug_level) {
     DLOG(NOTICE) << foo(&run_foo);
     DLOG(DEBUG) << foo(&run_foo);
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("vmodule", "").empty());
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("v", "1").empty());
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("vmodule", "").empty());
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("v", "1").empty());
     DVLOG(1) << foo(&run_foo);
     DVLOG2("a/b/c", 1) << foo(&run_foo);
 
@@ -470,7 +470,7 @@ void CheckFunctionName() {
     ASSERT_NE(std::string::npos, log_str.find("specified_file.cc:12345 log_at"));
     ::logging::SetLogSink(old_sink);
 
-    EXPECT_FALSE(GFLAGS_NS::SetCommandLineOption("v", "1").empty());
+    EXPECT_FALSE(GFLAGS_NAMESPACE::SetCommandLineOption("v", "1").empty());
     VLOG(100) << "test" << noflush;
     ASSERT_EQ(func_name, VLOG_STREAM(100).func());
 }
diff --git a/tools/BUILD b/tools/BUILD
index a836cb0449..3abad2412c 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -25,7 +25,6 @@ COPTS = [
     "-fPIC",
     "-Wno-unused-parameter",
     "-fno-omit-frame-pointer",
-    "-DGFLAGS_NS=google",
 ] + select({
     "//bazel/config:brpc_with_glog": ["-DBRPC_WITH_GLOG=1"],
     "//conditions:default": ["-DBRPC_WITH_GLOG=0"],
diff --git a/tools/parallel_http/parallel_http.cpp b/tools/parallel_http/parallel_http.cpp
index 6b863e0b63..24ae855cde 100644
--- a/tools/parallel_http/parallel_http.cpp
+++ b/tools/parallel_http/parallel_http.cpp
@@ -99,7 +99,7 @@ void* access_thread(void* void_args) {
 
 int main(int argc, char** argv) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     // if (FLAGS_path.empty() || FLAGS_path[0] != '/') {
     //     FLAGS_path = "/" + FLAGS_path;
diff --git a/tools/rpc_press/rpc_press.cpp b/tools/rpc_press/rpc_press.cpp
index 997a9fb03c..cb69ccfc16 100644
--- a/tools/rpc_press/rpc_press.cpp
+++ b/tools/rpc_press/rpc_press.cpp
@@ -97,7 +97,7 @@ bool set_press_options(pbrpcframework::PressOptions* options){
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     // set global log option
 
     if (FLAGS_dummy_port >= 0) {
diff --git a/tools/rpc_replay/rpc_replay.cpp b/tools/rpc_replay/rpc_replay.cpp
index 2065c238e5..c3cd7c4c3a 100644
--- a/tools/rpc_replay/rpc_replay.cpp
+++ b/tools/rpc_replay/rpc_replay.cpp
@@ -217,7 +217,7 @@ static void* replay_thread(void* arg) {
 
 int main(int argc, char* argv[]) {
     // Parse gflags. We recommend you to use gflags as well.
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
 
     if (FLAGS_dir.empty() ||
         !butil::DirectoryExists(butil::FilePath(FLAGS_dir))) {
diff --git a/tools/rpc_view/rpc_view.cpp b/tools/rpc_view/rpc_view.cpp
index 51de9150da..cdfb523d14 100644
--- a/tools/rpc_view/rpc_view.cpp
+++ b/tools/rpc_view/rpc_view.cpp
@@ -82,13 +82,13 @@ class ViewServiceImpl : public ViewService {
         const std::string* newtarget =
             server_cntl->http_request().uri().GetQuery("changetarget");
         if (newtarget) {
-            if (GFLAGS_NS::SetCommandLineOption("target", newtarget->c_str()).empty()) {
+            if (GFLAGS_NAMESPACE::SetCommandLineOption("target", newtarget->c_str()).empty()) {
                 server_cntl->SetFailed("Fail to change value of -target");
                 return;
             }
             target = *newtarget;
         } else {
-            if (!GFLAGS_NS::GetCommandLineOption("target", &target)) {
+            if (!GFLAGS_NAMESPACE::GetCommandLineOption("target", &target)) {
                 server_cntl->SetFailed("Fail to get value of -target");
                 return;
             }
@@ -153,15 +153,15 @@ class ViewServiceImpl : public ViewService {
 };
 
 int main(int argc, char* argv[]) {
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     if (FLAGS_target.empty() &&
         (argc != 2 || 
-         GFLAGS_NS::SetCommandLineOption("target", argv[1]).empty())) {
+         GFLAGS_NAMESPACE::SetCommandLineOption("target", argv[1]).empty())) {
         LOG(ERROR) << "Usage: ./rpc_view <ip>:<port>";
         return -1;
     }
     // This keeps ad-hoc creation of channels reuse previous connections.
-    GFLAGS_NS::SetCommandLineOption("defer_close_second", "10");
+    GFLAGS_NAMESPACE::SetCommandLineOption("defer_close_second", "10");
 
     brpc::Server server;
     server.set_version("rpc_view_server");
diff --git a/tools/trackme_server/trackme_server.cpp b/tools/trackme_server/trackme_server.cpp
index 541f544a98..76e09da9ea 100644
--- a/tools/trackme_server/trackme_server.cpp
+++ b/tools/trackme_server/trackme_server.cpp
@@ -88,7 +88,7 @@ class TrackMeServiceImpl : public brpc::TrackMeService {
 };
 
 int main(int argc, char* argv[]) {
-    GFLAGS_NS::ParseCommandLineFlags(&argc, &argv, true);
+    GFLAGS_NAMESPACE::ParseCommandLineFlags(&argc, &argv, true);
     
     brpc::Server server;
     server.set_version("trackme_server");