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

(grafted from e06edc0c7a4951327f0c95ebeebccba6879a6063)

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index 5a765f3..ac0b4bc 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -466,6 +466,23 @@ class ThreadTests(BaseTestCase):
         finally:
             sys.setcheckinterval(old_interval)
 
+    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):