It is clear looking at the source code that the Queue class uses time() and other non-monotonic timing sources. So if a queue get function is called with a timeout value and the system time is changed during that get it could end up waiting in the get for potentially days. The easiest way to reproduce is to set the timeout in the get to 5 minutes and which it is waiting on the queue to get an entry set the system clock back a few years. You will notice it will not exit the get.