bpo-37410: subprocess closes the process handle when done

Lib/subprocess.py

@@ -1300,6 +1300,13 @@ def _execute_child(self, args, executable, preexec_fn, close_fds,
             self.pid = pid
             _winapi.CloseHandle(ht)
 
+
+        def _set_returncode(self, exitcode):
+            self.returncode = exitcode
+            self._handle.Close()
+            self._handle = None
+
+
         def _internal_poll(self, _deadstate=None,
                 _WaitForSingleObject=_winapi.WaitForSingleObject,
                 _WAIT_OBJECT_0=_winapi.WAIT_OBJECT_0,
@@ -1313,7 +1320,8 @@ def _internal_poll(self, _deadstate=None,
             """
             if self.returncode is None:
                 if _WaitForSingleObject(self._handle, 0) == _WAIT_OBJECT_0:
-                    self.returncode = _GetExitCodeProcess(self._handle)
+                    exitcode = _GetExitCodeProcess(self._handle)
+                    self._set_returncode(exitcode)
             return self.returncode
 
 
@@ -1329,7 +1337,8 @@ def _wait(self, timeout):
                                                      timeout_millis)
                 if result == _winapi.WAIT_TIMEOUT:
                     raise TimeoutExpired(self.args, timeout)
-                self.returncode = _winapi.GetExitCodeProcess(self._handle)
+                exitcode = _winapi.GetExitCodeProcess(self._handle)
+                self._set_returncode(exitcode)
             return self.returncode
 
 
@@ -1417,7 +1426,7 @@ def terminate(self):
                 rc = _winapi.GetExitCodeProcess(self._handle)
                 if rc == _winapi.STILL_ACTIVE:
                     raise
-                self.returncode = rc
+                self._set_returncode(rc)
 
         kill = terminate
 
@@ -1638,7 +1647,7 @@ def _execute_child(self, args, executable, preexec_fn, close_fds,
                 try:
                     pid, sts = os.waitpid(self.pid, 0)
                     if pid == self.pid:
-                        self._handle_exitstatus(sts)
+                        self._set_returncode(sts)
                     else:
                         self.returncode = sys.maxsize
                 except ChildProcessError:
@@ -1674,7 +1683,7 @@ def _execute_child(self, args, executable, preexec_fn, close_fds,
                 raise child_exception_type(err_msg)
 
 
-        def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,
+        def _set_returncode(self, sts, _WIFSIGNALED=os.WIFSIGNALED,
                 _WTERMSIG=os.WTERMSIG, _WIFEXITED=os.WIFEXITED,
                 _WEXITSTATUS=os.WEXITSTATUS, _WIFSTOPPED=os.WIFSTOPPED,
                 _WSTOPSIG=os.WSTOPSIG):
@@ -1711,7 +1720,7 @@ def _internal_poll(self, _deadstate=None, _waitpid=os.waitpid,
                         return self.returncode  # Another thread waited.
                     pid, sts = _waitpid(self.pid, _WNOHANG)
                     if pid == self.pid:
-                        self._handle_exitstatus(sts)
+                        self._set_returncode(sts)
                 except OSError as e:
                     if _deadstate is not None:
                         self.returncode = _deadstate
@@ -1758,7 +1767,7 @@ def _wait(self, timeout):
                             (pid, sts) = self._try_wait(os.WNOHANG)
                             assert pid == self.pid or pid == 0
                             if pid == self.pid:
-                                self._handle_exitstatus(sts)
+                                self._set_returncode(sts)
                                 break
                         finally:
                             self._waitpid_lock.release()
@@ -1777,7 +1786,7 @@ def _wait(self, timeout):
                         # return 0 even without WNOHANG in odd situations.
                         # http://bugs.python.org/issue14396.
                         if pid == self.pid:
-                            self._handle_exitstatus(sts)
+                            self._set_returncode(sts)
             return self.returncode
 
 

Misc/NEWS.d/next/Library/2019-06-26-13-54-40.bpo-37410.H2R9oS.rst

@@ -0,0 +1,3 @@
+On Windows, :class:`subprocess.Popen` now closes the process handle when the
+process completes. Previously, it was only closed when the Popen object was
+destroyed.