Java 自定义线程池
Java 自定义线程池 https://www.cnblogs.com/yaoxiaowen/p/6576898.html
public ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler)
重点是对该构造方法的参数的理解