我有一个固定的线程池,我可以向其提交任务(仅限 5 线程)。我如何找出其中哪个 5 线程执行我的任务(例如“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?
}
}
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");
}
}
接受的答案回答了有关获取 a 线程 id 的问题,但它不允许您执行“Thread X of 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。
这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
使用模算术进行轻微调整将允许您正确执行“Y 的 X 线程”:
// 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
您可以使用 Thread.getCurrentThread.getId(),但是当记录器管理的 LogRecord 对象已经具有线程 Id 时,为什么要这样做呢?我认为您在某处缺少一个记录日志消息的线程 ID 的配置。
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++);
}
}
输出:
[ My thread # 0] Main INFO A pool thread is doing this task
当前线程获取方式有:
Thread t = Thread.currentThread();
获得 Thread 类对象 (t) 后,您可以使用 Thread 类方法获取所需的信息。
获取线程ID:
long tId = t.getId(); // e.g. 14291
线程名称获取:
String tName = t.getName(); // e.g. "pool-29-thread-7"
getId
的方法Thread.currentThread.getId()
自19起已被弃用。如果使用它会发出警告:
@Deprecated(since"19")
Deprecated
This method is not final and may be overriden to return a value that is not the thread ID. Use threadId() instead
推荐使用
Thread.currentThread.threadId()