[Python-checkins] GH-100133: fix `asyncio` subprocess losing `stderr` and `stdout` output (#100154)

[kumaraditya303]

https://github.com/python/cpython/commit/a7715ccfba5b86ab09f86ec56ac3755c93b46b48
commit: a7715ccfba5b86ab09f86ec56ac3755c93b46b48
branch: main
author: Kumar Aditya <59607654+kumaraditya303 at users.noreply.github.com>
committer: kumaraditya303 <59607654+kumaraditya303 at users.noreply.github.com>
date: 2022-12-21T15:20:26+05:30
summary:

GH-100133: fix `asyncio` subprocess losing `stderr` and `stdout` output (#100154)

files:
A Misc/NEWS.d/next/Library/2022-12-10-08-36-07.gh-issue-100133.g-zQlp.rst
M Lib/asyncio/base_subprocess.py
M Lib/test/test_asyncio/test_subprocess.py

diff --git a/Lib/asyncio/base_subprocess.py b/Lib/asyncio/base_subprocess.py
index e15bb4141fc0..4c9b0dd5653c 100644
--- a/Lib/asyncio/base_subprocess.py
+++ b/Lib/asyncio/base_subprocess.py
@@ -215,9 +215,6 @@ def _process_exited(self, returncode):
             # object. On Python 3.6, it is required to avoid a ResourceWarning.
             self._proc.returncode = returncode
         self._call(self._protocol.process_exited)
-        for p in self._pipes.values():
-            if p is not None:
-                p.pipe.close()
 
         self._try_finish()
 
diff --git a/Lib/test/test_asyncio/test_subprocess.py b/Lib/test/test_asyncio/test_subprocess.py
index 7411f735da3b..3830dea7d9ba 100644
--- a/Lib/test/test_asyncio/test_subprocess.py
+++ b/Lib/test/test_asyncio/test_subprocess.py
@@ -686,6 +686,23 @@ async def execute():
 
         self.assertIsNone(self.loop.run_until_complete(execute()))
 
+    def test_subprocess_communicate_stdout(self):
+        # See https://github.com/python/cpython/issues/100133
+        async def get_command_stdout(cmd, *args):
+            proc = await asyncio.create_subprocess_exec(
+                cmd, *args, stdout=asyncio.subprocess.PIPE,
+            )
+            stdout, _ = await proc.communicate()
+            return stdout.decode().strip()
+
+        async def main():
+            outputs = [f'foo{i}' for i in range(10)]
+            res = await asyncio.gather(*[get_command_stdout(sys.executable, '-c',
+                                        f'print({out!r})') for out in outputs])
+            self.assertEqual(res, outputs)
+
+        self.loop.run_until_complete(main())
+
 
 if sys.platform != 'win32':
     # Unix
diff --git a/Misc/NEWS.d/next/Library/2022-12-10-08-36-07.gh-issue-100133.g-zQlp.rst b/Misc/NEWS.d/next/Library/2022-12-10-08-36-07.gh-issue-100133.g-zQlp.rst
new file mode 100644
index 000000000000..881e6ed80fed
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-12-10-08-36-07.gh-issue-100133.g-zQlp.rst
@@ -0,0 +1 @@
+Fix regression in :mod:`asyncio` where a subprocess would sometimes lose data received from pipe.