newCachedThreadPool如何重用线程? [英] How newCachedThreadPool reuses threads?

问题描述

javadoc说Executors.newCachedThreadPool返回的服务会重用线程.这怎么可能? 线程只能通过调用start启动一次.那么他们如何实现呢?此服务的线程正在无限循环中运行，并且它们的Runnable -s是否按需替换?

The javadoc says that the service returned by Executors.newCachedThreadPool reuses threads. How is this possible? A thread can only be started once by calling start. So how do they implement it? Threads of this service are running in an infinite loop and their Runnable-s are replaced on demand?

推荐答案

一个Runnable可以调用另一个Runnable.

An Runnable can call another Runnable.

每个线程仅运行一个主Runnable，但该Runnable从共享的BlockingQueue中获取Runnable并对其进行调用，直到关闭为止.

Each thread runs only one main Runnable, but that Runnable takes Runnables from a shared BlockingQueue and calls these until it is shutdown.

简化了.

final BlockingQueue<Runnable> queue = ...

Runnable runs = new Runnable() { public void run() {
    while(running)
        queue.take().run();
}};

您可以阅读代码以查看其实际效果.

You can read the code to see how it really does it.

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