Issue 19158: a rare race in BoundedSemaphore could allow .release() too often.
(grafted from e06edc0c7a4951327f0c95ebeebccba6879a6063)
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 @@
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):
diff --git a/Lib/threading.py b/Lib/threading.py
index 72c8319..167f8c7 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -531,9 +531,11 @@
raise a ValueError.
"""
- if self._Semaphore__value >= self._initial_value:
- raise ValueError("Semaphore released too many times")
- return _Semaphore.release(self)
+ with self._cond:
+ if self._value >= self._initial_value:
+ raise ValueError("Semaphore released too many times")
+ self._value += 1
+ self._cond.notify()
def Event(*args, **kwargs):