如何从线程池获取线程id？

Question

我有一个固定的线程池，我提交任务（仅限于 5 线程）。我怎样才能找出其中的哪一个 5 线程执行我的任务（类似于"thread#3of 5 正在做这个任务"）？

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?
    }
}

Answer 1

使用Thread.currentThread()：

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

.

Answer 2

已接受的答案答案有关获取 a 线程ID的问题，但它不会让您执行“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。

这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Modulo算术的轻微调整将允许您正确执行“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 

.

Answer 3

您可以使用thread.getcurrentThread.getId（），但是当 Logrecord 由记录器管理的对象已具有Thread ID。我认为您在某处丢失了对日志消息的线程ID的配置。

Answer 4

如果你的类继承自 线程, ，可以使用方法 getName 和 setName 来命名每个线程。否则你可以添加一个 name 场到 MyTask, ，并在你的构造函数中初始化它。

Answer 5

如果使用日志记录，则线程名称将有用。 线程工厂有助于以下：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;

public class Main {

    static Logger LOG = LoggerFactory.getLogger(Main.class);

    static class MyTask implements Runnable {
        public void run() {
            LOG.info("A pool thread is doing this task");
        }
    }

    public static void main(String[] args) {
        ExecutorService taskExecutor = Executors.newFixedThreadPool(5, new MyThreadFactory());
        taskExecutor.execute(new MyTask());
        taskExecutor.shutdown();
    }
}

class MyThreadFactory implements ThreadFactory {
    private int counter;
    public Thread newThread(Runnable r) {
        return new Thread(r, "My thread # " + counter++);
    }
}

.

输出：

[   My thread # 0] Main         INFO  A pool thread is doing this task

.

Answer 6

当前线程获得：

Thread t = Thread.currentThread();

.

获得了线程类对象（t），您可以使用Thread类方法获取所需的信息。

线程ID Getting：

long tId = t.getId(); // e.g. 14291

.

线程名称getting：

String tName = t.getName(); // e.g. "pool-29-thread-7"

.