Issue 19158: a rare race in BoundedSemaphore could allow .release() too often.

1 files changed, 18 insertions, 0 deletions

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index 826acbb..4d30ee4 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -599,6 +599,24 @@ class ThreadTests(BaseTestCase):
             time.sleep(0.01)
         self.assertIn(LOOKING_FOR, repr(t)) # we waited at least 5 seconds
 
+    def test_BoundedSemaphore_limit(self):
+       # BoundedSemaphore should raise ValueError if released too often.
+       for limit in range(1, 10):
+           bs = threading.BoundedSemaphore(limit)
+           threads = [threading.Thread(target=bs.acquire)
+                      for _ in range(limit)]
+           for t in threads:
+               t.start()
+           for t in threads:
+               t.join()
+           threads = [threading.Thread(target=bs.release)
+                      for _ in range(limit)]
+           for t in threads:
+               t.start()
+           for t in threads:
+               t.join()
+           self.assertRaises(ValueError, bs.release)
+
 class ThreadJoinOnShutdown(BaseTestCase):
 
     def _run_and_join(self, script):