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authorTim Peters <tim@python.org>2013-10-09 01:55:51 (GMT)
committerTim Peters <tim@python.org>2013-10-09 01:55:51 (GMT)
commit7634e1cf9028ed5b21f0a97db45c91d8e8a159a6 (patch)
treead1fe9e98197bb607b5e833df4df62c34e75937e /Lib
parentee82d0b29355df56744962b51563f24c4d2a6102 (diff)
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Issue 19158: a rare race in BoundedSemaphore could allow .release() too often.
Diffstat (limited to 'Lib')
-rw-r--r--Lib/test/test_threading.py18
-rw-r--r--Lib/threading.py8
2 files changed, 23 insertions, 3 deletions
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index fef3314..0ebeb39 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -468,6 +468,24 @@ class ThreadTests(BaseTestCase):
self.assertEqual(0, status)
+ 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):
# Between fork() and exec(), only async-safe functions are allowed (issues
diff --git a/Lib/threading.py b/Lib/threading.py
index c98a006..3d4952b 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -283,9 +283,11 @@ class BoundedSemaphore(Semaphore):
self._initial_value = value
def release(self):
- if self._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()
class Event: