是否有使用当前线程的执行器服务？

concurrency java

2022-08-31 09:36:22

我所追求的是一种兼容的方式来配置线程池的使用。理想情况下，代码的其余部分根本不应该受到影响。我可以使用具有1个线程的线程池，但这不是我想要的。有什么想法吗？

ExecutorService es = threads == 0 ? new CurrentThreadExecutor() : Executors.newThreadPoolExecutor(threads);

// es.execute / es.submit / new ExecutorCompletionService(es) etc

答案 1

您可以使用Guava的MoreExecutors.newDirectExecutorService（）或MoreExecutors.directExecutor（）如果你不需要.ExecutorService

如果包含番石榴太重，你可以实现几乎同样好的东西：

public final class SameThreadExecutorService extends ThreadPoolExecutor {
  private final CountDownLatch signal = new CountDownLatch(1);

  private SameThreadExecutorService() {
    super(1, 1, 0, TimeUnit.DAYS, new SynchronousQueue<Runnable>(),
        new ThreadPoolExecutor.CallerRunsPolicy());
  }

  @Override public void shutdown() {
    super.shutdown();
    signal.countDown();
  }

  public static ExecutorService getInstance() {
    return SingletonHolder.instance;
  }

  private static class SingletonHolder {
    static ExecutorService instance = createInstance();    
  }

  private static ExecutorService createInstance() {
    final SameThreadExecutorService instance
        = new SameThreadExecutorService();

    // The executor has one worker thread. Give it a Runnable that waits
    // until the executor service is shut down.
    // All other submitted tasks will use the RejectedExecutionHandler
    // which runs tasks using the  caller's thread.
    instance.submit(new Runnable() {
        @Override public void run() {
          boolean interrupted = false;
          try {
            while (true) {
              try {
                instance.signal.await();
                break;
              } catch (InterruptedException e) {
                interrupted = true;
              }
            }
          } finally {
            if (interrupted) {
              Thread.currentThread().interrupt();
            }
          }
        }});
    return Executors.unconfigurableScheduledExecutorService(instance);
  }
}

答案 2

Java 8 风格：

Executor e = Runnable::run;