rusty_pool

Simple self growing / shrinking ThreadPool implementation based on crossbeam's multi-producer multi-consumer channels.

This ThreadPool has two different pool sizes; a core pool size filled with threads that live for as long as the channel and a max pool size which describes the maximum amount of worker threads that may live at the sime time. Those additional non-core threads have a specific keep_alive time described when creating the ThreadPool that defines how long such threads may be idle for without receiving any work before giving up and terminating their work loop.

This ThreadPool does not spawn any threads until a task is submitted to it. Then it will create a new thread for each task until the core pool size is full. After that a new thread will only be created upon an execute() call if the current pool is lower than the max pool size and there are no idle threads.

When creating a new worker thread this ThreadPool always checks whether the new worker is still required before starting the worker's main work queue in case an idle thread has opened up in the meantime or another thread has already created the worker.

Locks are only used for the join functions to lock the Condvar, apart from that this ThreadPool implementation fully relies on crossbeam and atomic operations.

The thread pool and its crossbeam channel can be destroyed by using the shutdown function, however that does not stop tasks that are already running but will terminate the thread the next time it will try to fetch work from the channel.