線程池（3）Executors.newCachedThreadPool

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例子：

ExecutorService es = Executors.newCachedThreadPool();        try {            for (int i = 0; i < 20; i++) {                Runnable syncRunnable = new Runnable() {                    @Override                    public void run() {                        log.info(Thread.currentThread().getName());                        try {                            Thread.sleep(2000);                        } catch (InterruptedException e) {                            e.printStackTrace();                        }                    }                };                es.execute(syncRunnable);            }        } finally {            es.shutdown();        }

運行結果：

            10:21:04.610 pool-1-thread-13            10:21:04.612 pool-1-thread-3            10:21:04.612 pool-1-thread-7            10:21:04.612 pool-1-thread-2            10:21:04.610 pool-1-thread-14            10:21:04.612 pool-1-thread-6            10:21:04.611 pool-1-thread-8            10:21:04.611 pool-1-thread-11            10:21:04.611 pool-1-thread-4            10:21:04.610 pool-1-thread-1            10:21:04.611 pool-1-thread-20            10:21:04.611 pool-1-thread-12            10:21:04.610 pool-1-thread-16            10:21:04.611 pool-1-thread-5            10:21:04.611 pool-1-thread-9            10:21:04.610 pool-1-thread-17            10:21:04.610 pool-1-thread-18            10:21:04.610 pool-1-thread-10            10:21:04.611 pool-1-thread-15            10:21:04.611 pool-1-thread-19

調用的調用的ThreadPoolExecutor：

public static ExecutorService newCachedThreadPool() {        return new ThreadPoolExecutor(0, Integer.MAX_VALUE,                                      60L, TimeUnit.SECONDS,                                      new SynchronousQueue<Runnable>());    }

corePoolSize=0，maximumPoolSize=Integer.MAX_VALUE

keepAliveTime=60秒

allowCoreThreadTimeout=false（預設）

因此，

• 核心線程數為0
• 每來一個任務，先查看緩衝池中是否有可用線程（沒超過60秒的），如果有，則用；沒有，則就建立一個新線程
• 因為核心線程數為0，池中的線程當達到60秒時，會逾時關閉，直到核心線程數=0

 

線程池（3）Executors.newCachedThreadPool