bpo-30966: concurrent.futures.Process.shutdown() closes queue (GH-19738)

Process.shutdown(wait=True) of concurrent.futures now closes
explicitly the result queue.

Lib/concurrent/futures/process.py

@@ -728,6 +728,8 @@ class ProcessPoolExecutor(_base.Executor):
         # objects that use file descriptors.
         self._executor_manager_thread = None
         self._call_queue = None
+        if self._result_queue is not None and wait:
+            self._result_queue.close()
         self._result_queue = None
         self._processes = None
 

Misc/NEWS.d/next/Library/2020-04-27-20-27-39.bpo-30966.Xmtlqu.rst

@@ -0,0 +1,2 @@
+``Process.shutdown(wait=True)`` of :mod:`concurrent.futures` now closes
+explicitly the result queue.