如何從線程池中獲取線程ID？

Question

我有一個固定的線程池，我提交任務（限於5個線程）。 如何找出這5個線程中的哪一個執行我的任務（類似“線程＃3 of 5正在執行此任務”）？

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

接受的答案回答了關於獲取線程 ID的問題，但它不會讓你的郵件“Y的主題X”。 線程ID在線程中是唯一的，但不一定從0或1開始。

以下是匹配問題的示例：

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();
  }
}

和輸出：

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

使用模運算的輕微調整將允許您正確執行“Y的線程X”：

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

新結果：

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（），但是當記錄器管理的LogRecord對象已經具有線程Id時，您為什么要這樣做？ 我認為你缺少一個記錄日志消息的線程ID的配置。

Answer 4

如果您的類繼承自Thread ，則可以使用方法getName和setName來命名每個線程。 否則，您只需向MyTask添加一個name字段，並在構造函數中初始化它。

Answer 5

如果您正在使用日志記錄，那么線程名稱將很有幫助。 一個線程工廠幫助這個：

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++);
    }
}

輸出：

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

Answer 6

有當前線程獲取的方式：

Thread t = Thread.currentThread();

獲得Thread類對象（t）后，您可以使用Thread類方法獲取所需的信息。

線程ID gettting：

long tId = t.getId();

線程名稱gettting：

String tName = t.getName();