gh-110036: multiprocessing Popen.terminate() catchs PermissionError

On Windows, multiprocessing Popen.terminate() now catchs
PermissionError and get the process exit code. If the process is
still running, raise again the PermissionError. Otherwise, the
process terminated as expected: store its exit code.

Lib/multiprocessing/popen_spawn_win32.py

@@ -14,6 +14,7 @@
 #
 #
 
+# Exit code used by Popen.terminate()
 TERMINATE = 0x10000
 WINEXE = (sys.platform == 'win32' and getattr(sys, 'frozen', False))
 WINSERVICE = sys.executable.lower().endswith("pythonservice.exe")
@@ -122,9 +123,15 @@ def terminate(self):
         if self.returncode is None:
             try:
                 _winapi.TerminateProcess(int(self._handle), TERMINATE)
-            except OSError:
-                if self.wait(timeout=1.0) is None:
+            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
 
     kill = terminate
 

Lib/test/_test_multiprocessing.py

@@ -557,13 +557,14 @@ def handler(*args):
 
     def test_terminate(self):
         exitcode = self._kill_process(multiprocessing.Process.terminate)
-        if os.name != 'nt':
-            self.assertEqual(exitcode, -signal.SIGTERM)
+        self.assertEqual(exitcode, -signal.SIGTERM)
 
     def test_kill(self):
         exitcode = self._kill_process(multiprocessing.Process.kill)
         if os.name != 'nt':
             self.assertEqual(exitcode, -signal.SIGKILL)
+        else:
+            self.assertEqual(exitcode, -signal.SIGTERM)
 
     def test_cpu_count(self):
         try:

Misc/NEWS.d/next/Library/2023-09-28-18-53-11.gh-issue-110036.fECxTj.rst

@@ -0,0 +1,5 @@
+On Windows, multiprocessing ``Popen.terminate()`` now catchs
+:exc:`PermissionError` and get the process exit code. If the process is
+still running, raise again the :exc:`PermissionError`. Otherwise, the
+process terminated as expected: store its exit code. Patch by Victor
+Stinner.