Question

我是一名努力学习Java编程的学生。我遇到了Java中的线程池，但我对以下线程池的工作原理感到困惑。我给了它5个工作线程。我的问题是，它是如何只有一个工作线程来完成我的工作？因为在我的输出中它只显示它只有一个执行任务的工作线程。我可以使用哪个公式来了解放入固定线程池的工作线程数？另外请明确告诉我工作线程的含义是什么。我无法解释是否有人问我。

public class Executement implements Runnable{
    Executement ec;

    private int taskId;

    public int men(int z,int x){
        int y = this.taskId*z;
        int w = this.taskId+x;
        return(y & w);
    }

    public void run(){
        for(int i = 0; i < 50; i++){
            int z = i*2;
            int m = i;
            System.out.println("Task ID :" + z + " performed by " + Thread.currentThread().getName());
            System.out.println("taskid: " + m + " performed by " + Thread.currentThread().getName());
        }
    }


    public static void main(String[] args) {
        ExecutorService service=Executors.newFixedThreadPool(5);
        service.submit(new Executement());    
        service.shutdown();
    }
}

这是输出的一部分：

Task ID :0 performed by pool-1-thread-1
taskid: 0 performed by pool-1-thread-1
Task ID :2 performed by pool-1-thread-1
taskid: 1 performed by pool-1-thread-1
Task ID :4 performed by pool-1-thread-1
taskid: 2 performed by pool-1-thread-1
Task ID :6 performed by pool-1-thread-1
taskid: 3 performed by pool-1-thread-1
Task ID :8 performed by pool-1-thread-1
taskid: 4 performed by pool-1-thread-1
Task ID :10 performed by pool-1-thread-1

Answer 1

你给了它5个线程和一个工作。 submit()更多Runnable个任务。

Answer 2

这将使用多个线程。

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

public class Executement implements Runnable {
    private int taskId;

    public Executement(int taskId) {
        this.taskId = taskId;
    }

    public void run() {
        System.out.println("task " + taskId + " performed by "
                + Thread.currentThread().getName());
    }

    public static void main(String[] args) {
        ExecutorService service = Executors.newFixedThreadPool(5);

        for (int i = 0; i < 50; i++) {
            service.submit(new Executement(i));
        }
        service.shutdown();
    }

}

不同之处在于您必须开始多个工作。只是在一个作业内部迭代不会使它产生多个线程。

Answer 3

将主要方法更改为

public static void main(String[] args) {
        ExecutorService service = Executors.newFixedThreadPool(5);

        for (int i = 0; i < 10; i++) {
            service.submit(new Executement());
        }
        service.submit(new Executement());
        service.shutdown();
    }

你只给了一个任务。给更多任务和线程池将启动更多线程。 查看部分输出

Task ID :0 performed by pool-1-thread-1
Task ID :0 performed by pool-1-thread-2
taskid: 0 performed by pool-1-thread-2
Task ID :2 performed by pool-1-thread-2
taskid: 1 performed by pool-1-thread-2
Task ID :4 performed by pool-1-thread-2
taskid: 2 performed by pool-1-thread-2
Task ID :6 performed by pool-1-thread-2
taskid: 3 performed by pool-1-thread-2
Task ID :8 performed by pool-1-thread-2
taskid: 0 performed by pool-1-thread-1
Task ID :0 performed by pool-1-thread-3
taskid: 0 performed by pool-1-thread-3
Task ID :2 performed by pool-1-thread-3
taskid: 1 performed by pool-1-thread-3
Task ID :4 performed by pool-1-thread-3
taskid: 2 performed by pool-1-thread-3
Task ID :6 performed by pool-1-thread-3
taskid: 3 performed by pool-1-thread-3
Task ID :8 performed by pool-1-thread-3
Task ID :0 performed by pool-1-thread-5
taskid: 0 performed by pool-1-thread-5
Task ID :2 performed by pool-1-thread-5
taskid: 1 performed by pool-1-thread-5
Task ID :4 performed by pool-1-thread-5

为什么这个threadpool只使用一个工作线程

3 个答案: