1 files changed, 7 insertions, 3 deletions
diff --git a/Lib/test/test_thread.py b/Lib/test/test_thread.py
index 02da94e75d..a45fb2fd5b 100644
--- a/Lib/test/test_thread.py
+++ b/Lib/test/test_thread.py
@@ -97,10 +97,14 @@ def task2(ident):
         if verbose:
             print 'task', ident, 'leaving barrier', i
     mutex.acquire()
-    running = running - 1
-    if running == 0:
-        done.release()
+    running -= 1
+    # Must release mutex before releasing done, else the main thread can
+    # exit and set mutex to None as part of global teardown; then
+    # mutex.release() raises AttributeError.
+    finished = running == 0
     mutex.release()
+    if finished:
+        done.release()
 
 print '\n*** Barrier Test ***'
 if done.acquire(0):