Hook to create a thread pool lazily. The hook is called if
thread_create_in_pool/4 discovers that the thread pool does not
exist. If the hook succeeds, thread_create_in_pool/4 retries
creating the thread. For example, we can use the following
declaration to create threads in the pool
media, which holds a
maximum of 20 threads.
:- multifile thread_pool:create_pool/1.
thread_pool_create(media, 20, ).