Build extensions in parallel (NVIDIA/apex#1882)

oraluben · forrestl111 · commit 0124107f820c · 2025-07-23T03:16:23.000Z
diff --git a/setup.py b/setup.py
@@ -16,8 +16,8 @@
 
 import os
 import subprocess
+import threading
 from packaging.version import parse, Version
-from typing import List, Set
 import warnings
 
 from setuptools import setup, find_packages
@@ -179,6 +179,44 @@ def get_nvcc_cuda_version(cuda_dir: str) -> Version:
 )
 ext_modules.append(fused_extension)
 
+
+parallel = None
+if 'EXT_PARALLEL' in os.environ:
+    try:
+        parallel = int(os.getenv('EXT_PARALLEL'))
+    finally:
+        pass
+
+
+# Prevent file conflicts when multiple extensions are compiled simultaneously
+class BuildExtensionSeparateDir(BuildExtension):
+    build_extension_patch_lock = threading.Lock()
+    thread_ext_name_map = {}
+
+    def finalize_options(self):
+        if parallel is not None:
+            self.parallel = parallel
+        super().finalize_options()
+
+    def build_extension(self, ext):
+        with self.build_extension_patch_lock:
+            if not getattr(self.compiler, "_compile_separate_output_dir", False):
+                compile_orig = self.compiler.compile
+
+                def compile_new(*args, **kwargs):
+                    return compile_orig(*args, **{
+                        **kwargs,
+                        "output_dir": os.path.join(
+                            kwargs["output_dir"],
+                            self.thread_ext_name_map[threading.current_thread().ident]),
+                    })
+                self.compiler.compile = compile_new
+                self.compiler._compile_separate_output_dir = True
+        self.thread_ext_name_map[threading.current_thread().ident] = ext.name
+        objects = super().build_extension(ext)
+        return objects
+
+
 setup(
     name='sageattention', 
     version='2.2.0',  
@@ -191,5 +229,5 @@ def get_nvcc_cuda_version(cuda_dir: str) -> Version:
     packages=find_packages(),
     python_requires='>=3.9',
     ext_modules=ext_modules,
-    cmdclass={"build_ext": BuildExtension},
+    cmdclass={"build_ext": BuildExtensionSeparateDir} if ext_modules else {},
 )
