Fix bug 544473 - "Queue module can deadlock".
Use try/finally to ensure all Queue locks remain stable.
Includes test case. Bugfix candidate.
diff --git a/Lib/test/test_queue.py b/Lib/test/test_queue.py
new file mode 100644
index 0000000..c0b94d5
--- /dev/null
+++ b/Lib/test/test_queue.py
@@ -0,0 +1,158 @@
+# Some simple Queue module tests, plus some failure conditions
+# to ensure the Queue locks remain stable
+import Queue
+import sys
+import threading
+import time
+
+from test_support import verify, TestFailed, verbose
+
+queue_size = 5
+
+# Execute a function that blocks, and in a seperate thread, a function that
+# triggers the release. Returns the result of the blocking function.
+class _TriggerThread(threading.Thread):
+ def __init__(self, fn, args):
+ self.fn = fn
+ self.args = args
+ self.startedEvent = threading.Event()
+ threading.Thread.__init__(self)
+ def run(self):
+ time.sleep(.1)
+ self.startedEvent.set()
+ self.fn(*self.args)
+
+def _doBlockingTest( block_func, block_args, trigger_func, trigger_args):
+ t = _TriggerThread(trigger_func, trigger_args)
+ t.start()
+ try:
+ return block_func(*block_args)
+ finally:
+ # If we unblocked before our thread made the call, we failed!
+ if not t.startedEvent.isSet():
+ raise TestFailed("blocking function '%r' appeared not to block" % (block_func,))
+ t.join(1) # make sure the thread terminates
+ if t.isAlive():
+ raise TestFailed("trigger function '%r' appeared to not return" % (trigger_func,))
+
+# A Queue subclass that can provoke failure at a moment's notice :)
+class FailingQueueException(Exception):
+ pass
+
+class FailingQueue(Queue.Queue):
+ def __init__(self, *args):
+ self.fail_next_put = False
+ self.fail_next_get = False
+ Queue.Queue.__init__(self, *args)
+ def _put(self, item):
+ if self.fail_next_put:
+ self.fail_next_put = False
+ raise FailingQueueException, "You Lose"
+ return Queue.Queue._put(self, item)
+ def _get(self):
+ if self.fail_next_get:
+ self.fail_next_get = False
+ raise FailingQueueException, "You Lose"
+ return Queue.Queue._get(self)
+
+def FailingQueueTest(q):
+ if not q.empty():
+ raise RuntimeError, "Call this function with an empty queue"
+ for i in range(queue_size-1):
+ q.put(i)
+ q.fail_next_put = True
+ # Test a failing non-blocking put.
+ try:
+ q.put("oops", block=0)
+ raise TestFailed("The queue didn't fail when it should have")
+ except FailingQueueException:
+ pass
+ q.put("last")
+ verify(q.full(), "Queue should be full")
+ q.fail_next_put = True
+ # Test a failing blocking put
+ try:
+ _doBlockingTest( q.put, ("full",), q.get, ())
+ raise TestFailed("The queue didn't fail when it should have")
+ except FailingQueueException:
+ pass
+ # Check the Queue isn't damaged.
+ # put failed, but get succeeded - re-add
+ q.put("last")
+ verify(q.full(), "Queue should be full")
+ q.get()
+ verify(not q.full(), "Queue should not be full")
+ q.put("last")
+ verify(q.full(), "Queue should be full")
+ # Test a blocking put
+ _doBlockingTest( q.put, ("full",), q.get, ())
+ # Empty it
+ for i in range(queue_size):
+ q.get()
+ verify(q.empty(), "Queue should be empty")
+ q.put("first")
+ q.fail_next_get = True
+ try:
+ q.get()
+ raise TestFailed("The queue didn't fail when it should have")
+ except FailingQueueException:
+ pass
+ verify(not q.empty(), "Queue should not be empty")
+ q.get()
+ verify(q.empty(), "Queue should be empty")
+ q.fail_next_get = True
+ try:
+ _doBlockingTest( q.get, (), q.put, ('empty',))
+ raise TestFailed("The queue didn't fail when it should have")
+ except FailingQueueException:
+ pass
+ # put succeeded, but get failed.
+ verify(not q.empty(), "Queue should not be empty")
+ q.get()
+ verify(q.empty(), "Queue should be empty")
+
+def SimpleQueueTest(q):
+ if not q.empty():
+ raise RuntimeError, "Call this function with an empty queue"
+ # I guess we better check things actually queue correctly a little :)
+ q.put(111)
+ q.put(222)
+ verify(q.get()==111 and q.get()==222, "Didn't seem to queue the correct data!")
+ for i in range(queue_size-1):
+ q.put(i)
+ verify(not q.full(), "Queue should not be full")
+ q.put("last")
+ verify(q.full(), "Queue should be full")
+ try:
+ q.put("full", block=0)
+ raise TestFailed("Didn't appear to block with a full queue")
+ except Queue.Full:
+ pass
+ # Test a blocking put
+ _doBlockingTest( q.put, ("full",), q.get, ())
+ # Empty it
+ for i in range(queue_size):
+ q.get()
+ verify(q.empty(), "Queue should be empty")
+ try:
+ q.get(block=0)
+ raise TestFailed("Didn't appear to block with an empty queue")
+ except Queue.Empty:
+ pass
+ # Test a blocking get
+ _doBlockingTest( q.get, (), q.put, ('empty',))
+
+def test():
+ q=Queue.Queue(queue_size)
+ # Do it a couple of times on the same queue
+ SimpleQueueTest(q)
+ SimpleQueueTest(q)
+ if verbose:
+ print "Simple Queue tests seemed to work"
+ q = FailingQueue(queue_size)
+ FailingQueueTest(q)
+ FailingQueueTest(q)
+ if verbose:
+ print "Failing Queue tests seemed to work"
+
+test()