From 3d284c081fc3042036adfe1bf2ce92c34d743b0b Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Sat, 19 Aug 2017 01:54:42 +0200
Subject: [PATCH] bpo-31234: test_threading: fix ref cycle (#3150)

test_bare_raise_in_brand_new_thread() now explicitly breaks a
reference cycle to not leak a dangling thread.
---
 Lib/test/test_threading.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index 0f3ac555c2d..800d26f71b2 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -1069,6 +1069,8 @@ class ThreadingExceptionTests(BaseTestCase):
         thread.join()
         self.assertIsNotNone(thread.exc)
         self.assertIsInstance(thread.exc, RuntimeError)
+        # explicitly break the reference cycle to not leak a dangling thread
+        thread.exc = None
 
 class TimerTests(BaseTestCase):