From ed9bca5d96a6b7e4951b14a430d25a5456cd5be0 Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Mon, 19 Feb 2024 15:47:18 +0100
Subject: [PATCH 1/2] gh-114914: Avoid keeping dead StreamWriter alive

In some cases we might cause a StreamWriter to stay alive even when the
application has dropped all references to it. This prevents us from
doing automatical cleanup, and complaining that the StreamWriter wasn't
properly closed.

Fortunately, the extra reference was never actually used for anything so
we can just drop it.
---
 Lib/asyncio/streams.py                        | 14 ++++-------
 Lib/test/test_asyncio/test_streams.py         | 23 +++++++++++++++++++
 ...-02-19-15-52-30.gh-issue-114914.M5-1d8.rst |  2 ++
 3 files changed, 29 insertions(+), 10 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-02-19-15-52-30.gh-issue-114914.M5-1d8.rst

diff --git a/Lib/asyncio/streams.py b/Lib/asyncio/streams.py
index df58b7a799a5ad..3fe52dbac25c91 100644
--- a/Lib/asyncio/streams.py
+++ b/Lib/asyncio/streams.py
@@ -201,7 +201,6 @@ def __init__(self, stream_reader, client_connected_cb=None, loop=None):
             # is established.
             self._strong_reader = stream_reader
         self._reject_connection = False
-        self._stream_writer = None
         self._task = None
         self._transport = None
         self._client_connected_cb = client_connected_cb
@@ -214,10 +213,8 @@ def _stream_reader(self):
             return None
         return self._stream_reader_wr()
 
-    def _replace_writer(self, writer):
+    def _replace_transport(self, transport):
         loop = self._loop
-        transport = writer.transport
-        self._stream_writer = writer
         self._transport = transport
         self._over_ssl = transport.get_extra_info('sslcontext') is not None
 
@@ -239,11 +236,8 @@ def connection_made(self, transport):
             reader.set_transport(transport)
         self._over_ssl = transport.get_extra_info('sslcontext') is not None
         if self._client_connected_cb is not None:
-            self._stream_writer = StreamWriter(transport, self,
-                                               reader,
-                                               self._loop)
-            res = self._client_connected_cb(reader,
-                                            self._stream_writer)
+            writer = StreamWriter(transport, self, reader, self._loop)
+            res = self._client_connected_cb(reader, writer)
             if coroutines.iscoroutine(res):
                 def callback(task):
                     if task.cancelled():
@@ -405,7 +399,7 @@ async def start_tls(self, sslcontext, *,
             ssl_handshake_timeout=ssl_handshake_timeout,
             ssl_shutdown_timeout=ssl_shutdown_timeout)
         self._transport = new_transport
-        protocol._replace_writer(self)
+        protocol._replace_transport(new_transport)
 
     def __del__(self, warnings=warnings):
         if not self._transport.is_closing():
diff --git a/Lib/test/test_asyncio/test_streams.py b/Lib/test/test_asyncio/test_streams.py
index 3c8cc5f3649180..313597b460f819 100644
--- a/Lib/test/test_asyncio/test_streams.py
+++ b/Lib/test/test_asyncio/test_streams.py
@@ -1129,6 +1129,29 @@ async def inner(httpd):
 
         self.assertEqual(messages, [])
 
+    def test_unclosed_server_resource_warnings(self):
+        async def inner(rd, wr):
+            with self.assertWarns(ResourceWarning) as cm:
+                del wr
+                gc.collect()
+                self.assertEqual(len(cm.warnings), 1)
+                self.assertTrue(str(cm.warnings[0].message).startswith("unclosed <StreamWriter"))
+
+        async def outer():
+            srv = await asyncio.start_server(inner, socket_helper.HOSTv4, 0)
+            async with srv:
+                addr = srv.sockets[0].getsockname()
+                with socket.create_connection(addr):
+                    # Give the loop some time to notice the connection
+                    await asyncio.sleep(0.1)
+
+        messages = []
+        self.loop.set_exception_handler(lambda loop, ctx: messages.append(ctx))
+
+        self.loop.run_until_complete(outer())
+
+        self.assertEqual(messages, [])
+
     def _basetest_unhandled_exceptions(self, handle_echo):
         port = socket_helper.find_unused_port()
 
diff --git a/Misc/NEWS.d/next/Library/2024-02-19-15-52-30.gh-issue-114914.M5-1d8.rst b/Misc/NEWS.d/next/Library/2024-02-19-15-52-30.gh-issue-114914.M5-1d8.rst
new file mode 100644
index 00000000000000..f7d392c8bceea3
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-02-19-15-52-30.gh-issue-114914.M5-1d8.rst
@@ -0,0 +1,2 @@
+Fix an issue where an abandoned :class:`StreamWriter` would not be garbage
+collected.

From cd0b45db1e17d15ae926e767df1736c1893d02e4 Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Tue, 27 Feb 2024 15:53:16 +0100
Subject: [PATCH 2/2] More reliable waiting for connection

---
 Lib/test/test_asyncio/test_streams.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_asyncio/test_streams.py b/Lib/test/test_asyncio/test_streams.py
index 313597b460f819..d28d0b931c2903 100644
--- a/Lib/test/test_asyncio/test_streams.py
+++ b/Lib/test/test_asyncio/test_streams.py
@@ -1131,6 +1131,7 @@ async def inner(httpd):
 
     def test_unclosed_server_resource_warnings(self):
         async def inner(rd, wr):
+            fut.set_result(True)
             with self.assertWarns(ResourceWarning) as cm:
                 del wr
                 gc.collect()
@@ -1143,11 +1144,12 @@ async def outer():
                 addr = srv.sockets[0].getsockname()
                 with socket.create_connection(addr):
                     # Give the loop some time to notice the connection
-                    await asyncio.sleep(0.1)
+                    await fut
 
         messages = []
         self.loop.set_exception_handler(lambda loop, ctx: messages.append(ctx))
 
+        fut = self.loop.create_future()
         self.loop.run_until_complete(outer())
 
         self.assertEqual(messages, [])