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gh-113009: Fix multiprocessing Process.terminate() on Windows #113128

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Merged
merged 1 commit into from
Dec 15, 2023
Merged

gh-113009: Fix multiprocessing Process.terminate() on Windows #113128

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54 changes: 30 additions & 24 deletions Lib/multiprocessing/popen_spawn_win32.py
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Original file line number Diff line number Diff line change
Expand Up @@ -101,37 +101,43 @@ def duplicate_for_child(self, handle):
return reduction.duplicate(handle, self.sentinel)

def wait(self, timeout=None):
if self.returncode is None:
if timeout is None:
msecs = _winapi.INFINITE
else:
msecs = max(0, int(timeout * 1000 + 0.5))

res = _winapi.WaitForSingleObject(int(self._handle), msecs)
if res == _winapi.WAIT_OBJECT_0:
code = _winapi.GetExitCodeProcess(self._handle)
if code == TERMINATE:
code = -signal.SIGTERM
self.returncode = code
if self.returncode is not None:
return self.returncode

if timeout is None:
msecs = _winapi.INFINITE
else:
msecs = max(0, int(timeout * 1000 + 0.5))

res = _winapi.WaitForSingleObject(int(self._handle), msecs)
if res == _winapi.WAIT_OBJECT_0:
code = _winapi.GetExitCodeProcess(self._handle)
if code == TERMINATE:
code = -signal.SIGTERM
self.returncode = code

return self.returncode

def poll(self):
return self.wait(timeout=0)

def terminate(self):
if self.returncode is None:
try:
_winapi.TerminateProcess(int(self._handle), TERMINATE)
except PermissionError:
# ERROR_ACCESS_DENIED (winerror 5) is received when the
# process already died.
code = _winapi.GetExitCodeProcess(int(self._handle))
if code == _winapi.STILL_ACTIVE:
raise
self.returncode = code
else:
self.returncode = -signal.SIGTERM
if self.returncode is not None:
return

try:
_winapi.TerminateProcess(int(self._handle), TERMINATE)
except PermissionError:
# ERROR_ACCESS_DENIED (winerror 5) is received when the
# process already died.
code = _winapi.GetExitCodeProcess(int(self._handle))
if code == _winapi.STILL_ACTIVE:
raise

# gh-113009: Don't set self.returncode. Even if GetExitCodeProcess()
# returns an exit code different than STILL_ACTIVE, the process can
# still be running. Only set self.returncode once WaitForSingleObject()
# returns WAIT_OBJECT_0 in wait().

kill = terminate

Expand Down
5 changes: 5 additions & 0 deletions Misc/NEWS.d/next/Windows/2023-12-14-19-00-29.gh-issue-113009.6LNdjz.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
:mod:`multiprocessing`: On Windows, fix a race condition in
``Process.terminate()``: no longer set the ``returncode`` attribute to
always call ``WaitForSingleObject()`` in ``Process.wait()``. Previously,
sometimes the process was still running after ``TerminateProcess()`` even if
``GetExitCodeProcess()`` is not ``STILL_ACTIVE``. Patch by Victor Stinner.