Program blocked in Queue.Queue.get and Queue.Queue.put

Kris krissteegmans at
Wed Jan 4 10:46:19 EST 2012

I have a program that is blocked and all threads are blocked on a
Queue.Queue.get or Queue.Queue.put method (on the same Queue.Queue

1 thread shows the below as its last entry in the stack:
File: "c:\python27\lib\", line 161, in get

2 threads show the below as its last entry in the stack:
File: "c:\python27\lib\", line 118, in put

According to me, this means both the Queue.Queue.not_full and
Queue.Queue.not_empty locks are taken, but no other thread seems to
have it. Of course, I don't access the locks my self directly.

I did send an KeyboardInterrupt to the main thread however. Could it
be that it was at that moment doing a Queue.Queue.put and it got
interrupted while it has the lock, but before it entered the try block
with the finally that releases the lock (so between line 118 and 119
in the file)?

If this is the case, how do I avoid that? Or is it a bug in the
Queue.Queue class?
If this is not the case, any clue what else could have happened?


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