I can’t quite understand your setup but you can prevent poolboy giving the worker to the next process by monitoring the worker and waiting for the :DOWN. GenServer.stop of the worker will provide this guarantee. This works because poolboy is link’ed to the worker processes, and exit signals are sent before monitor signals. Therefore poolboy is guaranteed to have the exit signal in it is message queue before process receives the :DOWN. This means poolboy will handle the exit signal first and replace the worker.