Question

我有一个固定的线程池，我将任务提交给（仅限于 5 个线程）。如何找出 5 线程中的哪一个执行我的任务（类似“ 5 的第3个线程正在执行此任务”）？

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?
    }
}

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

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“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

使用模运算进行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（），但是当记录器管理的LogRecord对象已经拥有线程ID时，您为什么要这样做？我认为你缺少一个记录日志消息的线程ID的配置。

Answer 4

如果您的类继承自Thread，则可以使用方法getName和setName来命名每个线程。否则，您只需向name添加MyTask字段，然后在构造函数中对其进行初始化。

Answer 5

如果您正在使用日志记录，那么线程名称将会很有帮助。线程工厂帮助解决这个问题：

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

有当前线程获取方法：

Thread t = Thread.currentThread();

获得Thread类对象（t）之后，您可以使用Thread类方法获取所需的信息。

线程ID获取：

long tId = t.getId();

线程名获取：

String tName = t.getName();

如何从线程池中获取线程ID？

6 个答案: