如何从线程池中获取线程 ID？

multithreading java executorservice threadpool executors

2022-08-31 07:47:30

我有一个固定的线程池，我向其提交任务（限制为5个线程）。我如何找出这 5 个线程中的哪一个执行我的任务（类似于“线程 #3 of 5 正在执行此任务”）？

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?
    }
}

答案 1

用：Thread.currentThread()

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

答案 2

接受的答案回答了有关获取线程 ID 的问题，但它不允许您执行“线程 X 的 Y”消息。线程 ID 在线程之间是唯一的，但不一定从 0 或 1 开始。

下面是一个匹配问题的示例：

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

使用模算法进行轻微调整将允许您正确执行“线程 X of Y”：

// 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