https://github.com/python/cpython/commit/bd473aa598c5161521a7018896dc124728214a6c
commit: bd473aa598c5161521a7018896dc124728214a6c
branch: main
author: Kumar Aditya <[email protected]>
committer: kumaraditya303 <[email protected]>
date: 2024-07-01T10:17:36+05:30
summary:
gh-87744: fix waitpid race while calling send_signal in asyncio (#121126)
asyncio earlier relied on subprocess module to send signals to the process,
this has some drawbacks one being that subprocess module unnecessarily calls
waitpid on child processes and hence it races with asyncio implementation which
internally uses child watchers. To mitigate this, now asyncio sends signals
directly to the process without going through the subprocess on non windows
systems. On Windows it fallbacks to subprocess module handling but on windows
there are no child watchers so this issue doesn't exists altogether.
files:
A Misc/NEWS.d/next/Library/2024-06-29-05-08-59.gh-issue-87744.rpF6Jw.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 6dbde2b696ad1f..9c2ba679ce2bf1 100644
--- a/Lib/asyncio/base_subprocess.py
+++ b/Lib/asyncio/base_subprocess.py
@@ -1,6 +1,9 @@
import collections
import subprocess
import warnings
+import os
+import signal
+import sys
from . import protocols
from . import transports
@@ -142,17 +145,31 @@ def _check_proc(self):
if self._proc is None:
raise ProcessLookupError()
- def send_signal(self, signal):
- self._check_proc()
- self._proc.send_signal(signal)
+ if sys.platform == 'win32':
+ def send_signal(self, signal):
+ self._check_proc()
+ self._proc.send_signal(signal)
+
+ def terminate(self):
+ self._check_proc()
+ self._proc.terminate()
+
+ def kill(self):
+ self._check_proc()
+ self._proc.kill()
+ else:
+ def send_signal(self, signal):
+ self._check_proc()
+ try:
+ os.kill(self._proc.pid, signal)
+ except ProcessLookupError:
+ pass
- def terminate(self):
- self._check_proc()
- self._proc.terminate()
+ def terminate(self):
+ self.send_signal(signal.SIGTERM)
- def kill(self):
- self._check_proc()
- self._proc.kill()
+ def kill(self):
+ self.send_signal(signal.SIGKILL)
async def _connect_pipes(self, waiter):
try:
diff --git a/Lib/test/test_asyncio/test_subprocess.py
b/Lib/test/test_asyncio/test_subprocess.py
index 23987c70ca7b63..54501300a29cf7 100644
--- a/Lib/test/test_asyncio/test_subprocess.py
+++ b/Lib/test/test_asyncio/test_subprocess.py
@@ -864,6 +864,21 @@ async def main():
self.loop.run_until_complete(main())
+ @unittest.skipIf(sys.platform != 'linux', "Linux only")
+ def test_subprocess_send_signal_race(self):
+ # See https://github.com/python/cpython/issues/87744
+ async def main():
+ for _ in range(10):
+ proc = await asyncio.create_subprocess_exec('sleep', '0.1')
+ await asyncio.sleep(0.1)
+ try:
+ proc.send_signal(signal.SIGUSR1)
+ except ProcessLookupError:
+ pass
+ self.assertNotEqual(await proc.wait(), 255)
+
+ self.loop.run_until_complete(main())
+
if sys.platform != 'win32':
# Unix
diff --git
a/Misc/NEWS.d/next/Library/2024-06-29-05-08-59.gh-issue-87744.rpF6Jw.rst
b/Misc/NEWS.d/next/Library/2024-06-29-05-08-59.gh-issue-87744.rpF6Jw.rst
new file mode 100644
index 00000000000000..c0b4f349fb6dac
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-06-29-05-08-59.gh-issue-87744.rpF6Jw.rst
@@ -0,0 +1 @@
+Fix waitpid race while calling :meth:`~asyncio.subprocess.Process.send_signal`
in asyncio. Patch by Kumar Aditya.
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