If a client calls getQueueInfo on a parent queue (e.g.: the root queue) and containers are completing then the RM can deadlock. getQueueInfo() locks the ParentQueue and then calls the child queues' getQueueInfo() methods in turn. However when a container completes, it locks the LeafQueue then calls back into the ParentQueue. When the two mix, it's a recipe for deadlock.
Stacktrace to follow.