[Python-checkins] bpo-38546: Fix concurrent.futures test_ressources_gced_in_workers() (GH-17652) (GH-17655)

[Victor Stinner]

https://github.com/python/cpython/commit/b0eb046cbd0dbb7b17f16aad6de20fac5305f387
commit: b0eb046cbd0dbb7b17f16aad6de20fac5305f387
branch: 3.8
author: Victor Stinner <vstinner at python.org>
committer: GitHub <noreply at github.com>
date: 2019-12-18T21:30:43+01:00
summary:

bpo-38546: Fix concurrent.futures test_ressources_gced_in_workers() (GH-17652) (GH-17655)

Fix test_ressources_gced_in_workers() of test_concurrent_futures:
explicitly stop the manager to prevent leaking a child process
running in the background after the test completes.

(cherry picked from commit 673c39331f844a80c465efd7cff88ac55c432bfb)

files:
A Misc/NEWS.d/next/Tests/2019-12-18-14-52-08.bpo-38546.2kxNuM.rst
M Lib/test/test_concurrent_futures.py

diff --git a/Lib/test/test_concurrent_futures.py b/Lib/test/test_concurrent_futures.py
index e01f2e4b78759..ac722981659d3 100644
--- a/Lib/test/test_concurrent_futures.py
+++ b/Lib/test/test_concurrent_futures.py
@@ -87,8 +87,7 @@ def my_method(self):
 
 
 class EventfulGCObj():
-    def __init__(self, ctx):
-        mgr = get_context(ctx).Manager()
+    def __init__(self, mgr):
         self.event = mgr.Event()
 
     def __del__(self):
@@ -848,12 +847,21 @@ def test_traceback(self):
     def test_ressources_gced_in_workers(self):
         # Ensure that argument for a job are correctly gc-ed after the job
         # is finished
-        obj = EventfulGCObj(self.ctx)
+        mgr = get_context(self.ctx).Manager()
+        obj = EventfulGCObj(mgr)
         future = self.executor.submit(id, obj)
         future.result()
 
         self.assertTrue(obj.event.wait(timeout=1))
 
+        # explicitly destroy the object to ensure that EventfulGCObj.__del__()
+        # is called while manager is still running.
+        obj = None
+        test.support.gc_collect()
+
+        mgr.shutdown()
+        mgr.join()
+
 
 create_executor_tests(ProcessPoolExecutorTest,
                       executor_mixins=(ProcessPoolForkMixin,
diff --git a/Misc/NEWS.d/next/Tests/2019-12-18-14-52-08.bpo-38546.2kxNuM.rst b/Misc/NEWS.d/next/Tests/2019-12-18-14-52-08.bpo-38546.2kxNuM.rst
new file mode 100644
index 0000000000000..d8ec7cabbbab8
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2019-12-18-14-52-08.bpo-38546.2kxNuM.rst
@@ -0,0 +1,3 @@
+Fix test_ressources_gced_in_workers() of test_concurrent_futures: explicitly
+stop the manager to prevent leaking a child process running in the background
+after the test completes.