?Workers)Query or manipulate the number of workers of the server identified by
Port. If Workers is unbound it is unified with the
number of running servers. If it is an integer greater than the current
size of the worker pool new workers are created with the same
specification as the running workers. If the number is less than the
current size of the worker pool, this predicate inserts a number of‘quit'
requests in the queue, discarding the excess workers as they finish
their jobs (i.e. no worker is abandoned while serving a client).
This can be used to tune the number of workers for performance.
Another possible application is to reduce the pool to one worker to
facilitate easier debugging.