Multi-threaded asynchronous execution mode, even though it can maximize the computing power of multi-core computer, but if not controlled, but would burden the system. Thread itself should take up memory space, a large number of threads and memory resources may cause Out of Memory. Even without such a situation, a lot of thread recovery will bring a lot of pressure to the GC.
In order to avoid duplication of creating a thread, appeared the thread pool thread to be multiplexed. Popular speak, when to have a job, it will take a thread to thread pool, when the work is completed, not directly close the thread, but this thread is returned to the thread pool for other tasks.
Overall next to the meticulous way, to discuss thread pool.
https://www.cnblogs.com/superfj/p/7544971.html
