setup_workers

Create more workers if necessary. Called by reap which is called regularly by the reap timer, so users don't typically need to call this.

reap

Check for worker threads that have exited and can be joined. If there are more worker threads than the normal number and they are idle, one worker thread (per reap call) is stopped.

This method is called regularly by the reap timer (see the reap_interval option to the constructor) and it's not typically called by users.