ResultDump.queue.put() can hang if the queue is full
sbws calls ResultDump.queue.put()
in blocking mode:
https://github.com/torproject/sbws/blob/ee64d76df54ceb3a3c9e1e2a797fd70d68bb0035/sbws/core/scanner.py#L303
But multiprocessing callbacks need to return immediately: https://docs.python.org/3/library/multiprocessing.html#multiprocessing.pool.Pool.apply_async
So sbws should call put() without blocking, or with a (very small) timeout: https://docs.python.org/3/library/queue.html#queue.Queue.put