線程池（2）Executors.newFixedThreadPool

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例子：

ExecutorService es = Executors.newFixedThreadPool(5);        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：         *  10:20:14.630 pool-1-thread-5            10:20:14.630 pool-1-thread-1            10:20:14.632 pool-1-thread-4            10:20:14.630 pool-1-thread-2            10:20:14.630 pool-1-thread-3            10:20:16.635 pool-1-thread-4            10:20:16.635 pool-1-thread-5            10:20:16.635 pool-1-thread-1            10:20:16.636 pool-1-thread-2            10:20:16.637 pool-1-thread-3            10:20:18.637 pool-1-thread-3            10:20:18.638 pool-1-thread-4            10:20:18.641 pool-1-thread-5            10:20:18.641 pool-1-thread-1            10:20:18.642 pool-1-thread-2            10:20:20.638 pool-1-thread-3            10:20:20.639 pool-1-thread-4            10:20:20.641 pool-1-thread-5            10:20:20.642 pool-1-thread-1            10:20:20.642 pool-1-thread-2

調用的ThreadPoolExecutor：

public static ExecutorService newFixedThreadPool(int nThreads) {        return new ThreadPoolExecutor(nThreads, nThreads,                                      0L, TimeUnit.MILLISECONDS,                                      new LinkedBlockingQueue<Runnable>());    }

 

corePoolSize=maximumPoolSize=5

keepAliveTime=0

allowCoreThreadTimeout=false（預設）

因此，

• 線程池中的線程數永遠是5，永久存活。
• 對於新任務，當隊列未滿時，插入隊列；當隊列已滿時，預設執行AbortPolicy，即拋出異常。
• 支援線程reuse

 

線程池（2）Executors.newFixedThreadPool