使用RunTime.getRunTime().addShutdownHook優雅關閉線程池

有時候咱們用到的程序不必定老是在JVM裏面駐守,可能調用完就不用了,釋放資源.

RunTime.getRunTime().addShutdownHook的做用就是在JVM銷燬前執行的一個線程.固然這個線程依然要本身寫.

利用這個性質,若是咱們以前定義了一系列的線程池供程序自己使用,那麼就能夠在這個最後執行的線程中把這些線程池優雅的關閉掉.

好比咱們定義了一個線程池

private ExecutorService streamThreadPool = Executors.newFixedThreadPool(streamNum);

而後咱們須要對它進行優雅關閉

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

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

/**
 * 優雅關閉線程池
 * @param threadPool
 * @param alias
 */
private void shutdownThreadPool(ExecutorService threadPool, String alias) {
   log.info("Start to shutdown the thead pool: {}", alias);

   threadPool.shutdown(); // 使新任務沒法提交.
   try {
      // 等待未完成任務結束
      if (!threadPool.awaitTermination(60, TimeUnit.SECONDS)) {
         threadPool.shutdownNow(); // 取消當前執行的任務
         log.warn("Interrupt the worker, which may cause some task inconsistent. Please check the biz logs.");

         // 等待任務取消的響應
         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) {
      // 從新取消當前線程進行中斷
      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.");

      // 保留中斷狀態
      Thread.currentThread().interrupt();
   }

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

這樣咱們就能夠在JVM銷燬前不管有沒有執行的線程都會進行中斷,而後關閉線程池.