gh-87063: Add closed attribute to multiprocessing.Process

Doc/library/multiprocessing.rst

@@ -673,6 +673,15 @@ The :mod:`multiprocessing` package mostly replicates the API of the
 
       .. versionadded:: 3.7
 
+   .. method:: closed()
+
+      Return whether the process is closed.
+
+      Roughly, a process object is considered closed when :meth:`close`
+      is called on it.
+
+      .. versionadded:: 3.14
+
    .. method:: close()
 
       Close the :class:`Process` object, releasing all resources associated

Lib/multiprocessing/process.py

@@ -169,6 +169,13 @@ def is_alive(self):
             _children.discard(self)
             return False
 
+    @property
+    def closed(self):
+        '''
+        Return whether process is closed
+        '''
+        return self._closed
+
     def close(self):
         '''
         Close the Process object.

Lib/test/_test_multiprocessing.py

@@ -649,6 +649,21 @@ def _test_close(cls, rc=0, q=None):
             q.get()
         sys.exit(rc)
 
+    def test_is_close(self):
+        if self.TYPE == "threads":
+            self.skipTest('test not appropriate for {}'.format(self.TYPE))
+        def _test_task():
+            pass
+        p = self.Process(target=_test_task)
+        self.assertFalse(p.closed)
+        p.close()
+        self.assertTrue(p.closed)
+
+        wr = weakref.ref(p)
+        del p
+        gc.collect()
+        self.assertIs(wr(), None)
+
     def test_close(self):
         if self.TYPE == "threads":
             self.skipTest('test not appropriate for {}'.format(self.TYPE))

Misc/NEWS.d/next/Library/2024-10-22-19-52-15.gh-issue-87063.fR-wJa.rst

@@ -0,0 +1,2 @@
+Add the ``closed()`` in the :class:`multiprocessing.Process` to
+determine whether the process is closed.