python · vstinner · Aug 10, 2017 · Aug 10, 2017 · Aug 10, 2017
diff --git a/Lib/socketserver.py b/Lib/socketserver.py
@@ -547,7 +547,7 @@ class ForkingMixIn:
        active_children = None
        max_children = 40

-        def collect_children(self):
+        def collect_children(self, *, blocking=False):
            """Internal routine to wait for children that have exited."""
            if self.active_children is None:
                return
@@ -571,7 +571,8 @@ def collect_children(self):
            # Now reap all defunct children.
            for pid in self.active_children.copy():
                try:
-                    pid, _ = os.waitpid(pid, os.WNOHANG)
+                    flags = 0 if blocking else os.WNOHANG
+                    pid, _ = os.waitpid(pid, flags)
                    # if the child hasn't exited yet, pid will be 0 and ignored by
                    # discard() below
                    self.active_children.discard(pid)
@@ -620,6 +621,10 @@ def process_request(self, request, client_address):
                    finally:
                        os._exit(status)

+        def server_close(self):
+            super().server_close()
+            self.collect_children(blocking=True)
+

 class ThreadingMixIn:
    """Mix-in class to handle each request in a new thread."""

diff --git a/Lib/test/test_socketserver.py b/Lib/test/test_socketserver.py
@@ -144,6 +144,10 @@ def run_server(self, svrcls, hdlrbase, testfunc):
        t.join()
        server.server_close()
        self.assertEqual(-1, server.socket.fileno())
+        if HAVE_FORKING and isinstance(server, socketserver.ForkingMixIn):
+            # bpo-31151: Check that ForkingMixIn.server_close() waits until
+            # all children completed
+            self.assertFalse(server.active_children)
        if verbose: print("done")

    def stream_examine(self, proto, addr):
@@ -371,10 +375,7 @@ def wait_done(self):

 if HAVE_FORKING:
    class ForkingErrorTestServer(socketserver.ForkingMixIn, BaseErrorTestServer):
-        def wait_done(self):
-            [child] = self.active_children
-            os.waitpid(child, 0)
-            self.active_children.clear()
+        pass


 class SocketWriterTest(unittest.TestCase):

diff --git a/Misc/NEWS.d/next/Library/2017-08-10-13-20-02.bpo-31151.730VBI.rst b/Misc/NEWS.d/next/Library/2017-08-10-13-20-02.bpo-31151.730VBI.rst
@@ -0,0 +1,2 @@
+socketserver.ForkingMixIn.server_close() now waits until all child processes
+completed to prevent leaking zombie processes.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		socketserver.ForkingMixIn.server_close() now waits until all child processes
		completed to prevent leaking zombie processes.