ExecutorService的OOM坑

ExecutorService有下面几种创建方式

                   Executors.newCachedThreadPool();

                   Executors.newFixedThreadPool()

                   Executors.newScheduledThreadPool()

                   Executors.newSingleThreadExecutor()

                   Executors.newSingleThreadScheduledExecutor()

抽取其中一个方法查看源码：

publicstatic ExecutorService newFixedThreadPool(int nThreads) {

    return new ThreadPoolExecutor(nThreads,nThreads,

                                  0L, TimeUnit.MILLISECONDS,

                                  newLinkedBlockingQueue<Runnable>());

}

   /**

     * Creates a {@code LinkedBlockingQueue}with a capacity of

     * {@link Integer#MAX_VALUE}.

     */

   publicLinkedBlockingQueue(){

        this(Integer.MAX_VALUE);

    }

 

   /**

     * A constant holding the maximum value an{@code int} can

     * have, 2³¹-1.

     */

    public static final int   MAX_VALUE = 0x7fffffff;

 

 

由上面的方法参数知道，Executors创建的ExecutorService并不能设置控制消息队列的长列，默认长度是2^31，当线程处理速度较慢且并发任务太多时，任务队列的任务将不断堆积，就可能引起OOM。因此建议直接

 

ThreadPoolExecutor executor = new TThreadPoolExecutor(int corePoolSize,

                              intmaximumPoolSize,

                              longkeepAliveTime,

                              TimeUnit unit,

                             BlockingQueue<Runnable> workQueue)

这样就可以灵活定制队列，建议使用new ThreadPoolExecutor。