bpo-30966: Add multiprocessing.SimpleQueue.close() (GH-19735)

Add a new close() method to multiprocessing.SimpleQueue to explicitly
close the queue.

Automerge-Triggered-By: @pitrou

2 files changed, 18 insertions, 0 deletions

diff --git a/Lib/multiprocessing/queues.py b/Lib/multiprocessing/queues.py
index c0a284d..a290181 100644
--- a/Lib/multiprocessing/queues.py
+++ b/Lib/multiprocessing/queues.py
@@ -346,6 +346,10 @@ class SimpleQueue(object):
         else:
             self._wlock = ctx.Lock()
 
+    def close(self):
+        self._reader.close()
+        self._writer.close()
+
     def empty(self):
         return not self._poll()
 
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 083ad53..dd894f2 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -5244,6 +5244,20 @@ class TestSimpleQueue(unittest.TestCase):
 
         proc.join()
 
+    def test_close(self):
+        queue = multiprocessing.SimpleQueue()
+        queue.close()
+        # closing a queue twice should not fail
+        queue.close()
+
+    # Test specific to CPython since it tests private attributes
+    @test.support.cpython_only
+    def test_closed(self):
+        queue = multiprocessing.SimpleQueue()
+        queue.close()
+        self.assertTrue(queue._reader.closed)
+        self.assertTrue(queue._writer.closed)
+
 
 class TestPoolNotLeakOnFailure(unittest.TestCase):