如何从线程池获得线程 ID？

我有一个固定的线程池，我提交任务(限于 5线程)。如何找出哪个 5线程执行我的任务(类似于“ 5的线程 # 3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?
}
}
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最佳答案

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");
}
}
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如果类继承自 线头，则可以使用方法 getName和 setName来命名每个线程。否则，您可以只添加一个 name字段到 MyTask，并在构造函数中初始化它。

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您可以使用 Thread.getCurrentThread.getId () ，但是当记录器管理的 日志记录对象已经具有线程 Id 时，为什么还要这样做呢。我认为您缺少一个配置，该配置记录日志消息的线程 ID。

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接受的答案回答了关于获取 一线程 id 的问题，但是它不允许您执行“ ThreadXofY”消息。线程 id 在线程之间是唯一的，但不一定从0或1开始。

下面是一个与问题相匹配的例子:

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();
}
}

以及输出:

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

使用模数算法稍微调整一下就可以正确地执行“ 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
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如果您正在使用日志记录，那么线程名称将是有帮助的。 一个线程工厂可以帮助解决这个问题:

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++);
}
}

产出:

[   My thread # 0] Main         INFO  A pool thread is doing this task
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有一种获得当前线程的方法:

Thread t = Thread.currentThread();

在得到 Thread 类对象(t)之后，就能够使用 Thread 类方法获得所需的信息。

获取线程 ID:

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

获取线程名称:

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

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