A thread pool is an object that maintains a pool of worker threads to perform time consuming operations in parallel. It assigns jobs to the threads by putting them in a work request queue, where they are picked up by the next available thread. This then performs the requested operation in the background and puts the results in another queue. The thread pool object can then collect the results from all threads from this queue as soon as they become available or after all threads have finished their work. It's then possible to define callbacks to handle each result as it comes in. NOTE: This module is regarded as an extended example, not as a finished product. Feel free to adapt it too your needs.