使用RunTime.getRunTime().addShutdownHook优雅关闭线程池

有时候咱们用到的程序不必定老是在JVM里面驻守,可能调用完就不用了,释放资源.

RunTime.getRunTime().addShutdownHook的做用就是在JVM销毁前执行的一个线程.固然这个线程依然要本身写.

利用这个性质,若是咱们以前定义了一系列的线程池供程序自己使用,那么就能够在这个最后执行的线程中把这些线程池优雅的关闭掉.

好比咱们定义了一个线程池

private ExecutorService streamThreadPool = Executors.newFixedThreadPool(streamNum);

而后咱们须要对它进行优雅关闭

Runtime.getRuntime().addShutdownHook(new Thread() {
   public void run() {
      shutdownGracefully();
   }
});

public void shutdownGracefully() {
   shutdownThreadPool(streamThreadPool, "main-pool");
}

/**
 * 优雅关闭线程池
 * @param threadPool
 * @param alias
 */
private void shutdownThreadPool(ExecutorService threadPool, String alias) {
   log.info("Start to shutdown the thead pool: {}", alias);

   threadPool.shutdown(); // 使新任务没法提交.
   try {
      // 等待未完成任务结束
      if (!threadPool.awaitTermination(60, TimeUnit.SECONDS)) {
         threadPool.shutdownNow(); // 取消当前执行的任务
         log.warn("Interrupt the worker, which may cause some task inconsistent. Please check the biz logs.");

         // 等待任务取消的响应
         if (!threadPool.awaitTermination(60, TimeUnit.SECONDS))
            log.error("Thread pool can't be shutdown even with interrupting worker threads, which may cause some task inconsistent. Please check the biz logs.");
      }
   } catch (InterruptedException ie) {
      // 从新取消当前线程进行中断
      threadPool.shutdownNow();
      log.error("The current server thread is interrupted when it is trying to stop the worker threads. This may leave an inconcistent state. Please check the biz logs.");

      // 保留中断状态
      Thread.currentThread().interrupt();
   }

   log.info("Finally shutdown the thead pool: {}", alias);
}

这样咱们就能够在JVM销毁前不管有没有执行的线程都会进行中断,而后关闭线程池.