From acc13ecf603cb31da2b779527098de9764526014 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 12 Oct 2020 06:30:48 +0200
Subject: [PATCH] bpo-41739: Fix
 test_logging.test_race_between_set_target_and_flush() (GH-22655) (GH-22656)

The test now waits until all threads complete to avoid leaking
running threads.

Also, use regular threads rather than daemon threads.

(cherry picked from commit 13ff396c019d548ba181cf22c6f39309a300723c)
(cherry picked from commit f5393dc2a0ced7bf670ebc56b5fd10a3eb328d1a)

Co-authored-by: Victor Stinner <vstinner@python.org>
---
 Lib/test/test_logging.py                      | 21 ++++++++++++-------
 .../2020-10-12-00-11-47.bpo-41739.wSCc4K.rst  |  2 ++
 2 files changed, 15 insertions(+), 8 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Tests/2020-10-12-00-11-47.bpo-41739.wSCc4K.rst

diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index cea51b455eed25..b9392aefd44762 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -1177,22 +1177,27 @@ def test_race_between_set_target_and_flush(self):
         class MockRaceConditionHandler:
             def __init__(self, mem_hdlr):
                 self.mem_hdlr = mem_hdlr
+                self.threads = []
 
             def removeTarget(self):
                 self.mem_hdlr.setTarget(None)
 
             def handle(self, msg):
-                t = threading.Thread(target=self.removeTarget)
-                t.daemon = True
-                t.start()
+                thread = threading.Thread(target=self.removeTarget)
+                self.threads.append(thread)
+                thread.start()
 
         target = MockRaceConditionHandler(self.mem_hdlr)
-        self.mem_hdlr.setTarget(target)
+        try:
+            self.mem_hdlr.setTarget(target)
 
-        for _ in range(10):
-            time.sleep(0.005)
-            self.mem_logger.info("not flushed")
-            self.mem_logger.warning("flushed")
+            for _ in range(10):
+                time.sleep(0.005)
+                self.mem_logger.info("not flushed")
+                self.mem_logger.warning("flushed")
+        finally:
+            for thread in target.threads:
+                support.join_thread(thread)
 
 
 class ExceptionFormatter(logging.Formatter):
diff --git a/Misc/NEWS.d/next/Tests/2020-10-12-00-11-47.bpo-41739.wSCc4K.rst b/Misc/NEWS.d/next/Tests/2020-10-12-00-11-47.bpo-41739.wSCc4K.rst
new file mode 100644
index 00000000000000..7aee2b94444727
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2020-10-12-00-11-47.bpo-41739.wSCc4K.rst
@@ -0,0 +1,2 @@
+Fix test_logging.test_race_between_set_target_and_flush(): the test now
+waits until all threads complete to avoid leaking running threads.