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

1 files changed, 5 insertions, 3 deletions

diff --git a/Lib/threading.py b/Lib/threading.py
index 26d1018d3e..b99d0e9353 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -289,9 +289,11 @@ 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: