python · vstinner · Jul 10, 2017 · Jul 10, 2017
diff --git a/Lib/multiprocessing/queues.py b/Lib/multiprocessing/queues.py
@@ -169,14 +169,7 @@ def _start_thread(self):
        self._thread.start()
        debug('... done self._thread.start()')

-        # On process exit we will wait for data to be flushed to pipe.
-        #
-        # However, if this process created the queue then all
-        # processes which use the queue will be descendants of this
-        # process.  Therefore waiting for the queue to be flushed
-        # is pointless once all the child processes have been joined.
-        created_by_this_process = (self._opid == os.getpid())
-        if not self._joincancelled and not created_by_this_process:
+        if not self._joincancelled:
            self._jointhread = Finalize(
                self._thread, Queue._finalize_join,
                [weakref.ref(self._thread)],

diff --git a/Misc/NEWS.d/next/Library/2017-07-10-12-14-22.bpo-30886.nqQj34.rst b/Misc/NEWS.d/next/Library/2017-07-10-12-14-22.bpo-30886.nqQj34.rst
@@ -0,0 +1,3 @@
+Fix multiprocessing.Queue.join_thread(): it now waits until the thread
+completes, even if the thread was started by the same process which created
+the queue.