如何从线程池中获取线程ID?

问题

我有一个固定的线程池,我提交任务(限于5threads)。我怎样才能找出那些执行我的任务中的哪一个(例如"线程#3 of5执行此任务")?

ExecutorService taskExecutor = Executors.newFixedThreadPool(5);

//in infinite loop:
taskExecutor.execute(new MyTask());
....

private class MyTask implements Runnable {
    public void run() {
        logger.debug("Thread # XXX is doing this task");//how to get thread id?
    }
}

#1 热门回答(194 赞)

UsingThread.currentThread()

private class MyTask implements Runnable {
    public void run() {
        long threadId = Thread.currentThread().getId();
        logger.debug("Thread # " + threadId + " is doing this task");
    }
}

#2 热门回答(22 赞)

接受的答案回答了关于getathread id的问题,但它不允许你做"Y的线程X"消息。线程ID在线程中是唯一的,但不一定从0或1开始。

以下是与问题匹配的示例:

import java.util.concurrent.*;
class ThreadIdTest {

  public static void main(String[] args) {

    final int numThreads = 5;
    ExecutorService exec = Executors.newFixedThreadPool(numThreads);

    for (int i=0; i<10; i++) {
      exec.execute(new Runnable() {
        public void run() {
          long threadId = Thread.currentThread().getId();
          System.out.println("I am thread " + threadId + " of " + numThreads);
        }
      });
    }

    exec.shutdown();
  }
}

和输出:

burhan@orion:/dev/shm$ javac ThreadIdTest.java && java ThreadIdTest
I am thread 8 of 5
I am thread 9 of 5
I am thread 10 of 5
I am thread 8 of 5
I am thread 9 of 5
I am thread 11 of 5
I am thread 8 of 5
I am thread 9 of 5
I am thread 10 of 5
I am thread 12 of 5

使用模运算的轻微调整将允许你正确执行"Y的线程X":

// modulo gives zero-based results hence the +1
long threadId = Thread.currentThread().getId()%numThreads +1;

新结果:

burhan@orion:/dev/shm$ javac ThreadIdTest.java && java ThreadIdTest  
I am thread 2 of 5 
I am thread 3 of 5 
I am thread 3 of 5 
I am thread 3 of 5 
I am thread 5 of 5 
I am thread 1 of 5 
I am thread 4 of 5 
I am thread 1 of 5 
I am thread 2 of 5 
I am thread 3 of 5

#3 热门回答(6 赞)

你可以使用Thread.getCurrentThread.getId(),但是当记录器管理的LogRecord对象已经具有线程Id时,你为什么要这样做呢?我认为你缺少一个记录日志消息的线程ID的配置。