如何使多个线程运行并行执行，以便一个接一个地执行线程

Question

我正在尝试实现并行线程执行。例如

t1, t2, and t3 are three threads , each performing a task to print multiplication table. I want to execute them in a sequence

--------------------------------
|   t1    |    t2    |    t3   | 
--------------------------------
|   2     |     3    |     4   |
|   4     |     6    |     8   |
|   6     |     9    |    12   |
|   ..    |    ..    |   ..    |
|------------------------------|

执行顺序：t1--> t2--> t3 --> t1

到目前为止，我能够创建三个独立执行任务的线程

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

public class SynchronizationExample1 {
    public static void main(String[] args) {
        ExecutorService es = Executors.newFixedThreadPool(3);   
        for(int i=1; i<=10; i++){
            es.execute(new Task(i));
        }
        es.shutdown();

        while(!es.isTerminated()){

        }
        System.out.println("finished all task");
    }
}

任务class

public class Task implements Runnable {
    private int i; 
    public Task(int i){
        this.i = i;
    }

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+ "Start counter = " + i);
        processMessage();
        System.out.println(Thread.currentThread().getName()+ "End counter");
    }

    public void processMessage(){
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}

输出：

pool-1-thread-1Start counter = 1
pool-1-thread-3Start counter = 3
pool-1-thread-2Start counter = 2
pool-1-thread-1End counter
pool-1-thread-1Start counter = 4
pool-1-thread-3End counter
pool-1-thread-3Start counter = 5
pool-1-thread-2End counter
pool-1-thread-2Start counter = 6
pool-1-thread-1End counter
pool-1-thread-1Start counter = 7
pool-1-thread-3End counter
pool-1-thread-3Start counter = 8
pool-1-thread-2End counter
pool-1-thread-2Start counter = 9
pool-1-thread-1End counter
pool-1-thread-1Start counter = 10
pool-1-thread-3End counter
pool-1-thread-2End counter
pool-1-thread-1End counter
finished all task

Answer 1

I am trying to acheive parallal thread execution. for example t1, t2, and t3 are three threads , each performing a task to print multiplication table. I want to execute them in a sequence.

这是一种自相矛盾的说法。

你可以并行或顺序做事，但不能同时做。（就像运行同时骑自行车！）

正如@Thilo 所述，简单、实用（也是最佳）的解决方案是不要使用多线程来执行此操作。只需使用一个线程和一个 for 循环。

如果您打算使用多个线程执行此操作，则需要线程同步。（这似乎是您当前代码的问题。您没有同步......只有三个 "free running" 线程和 sleep() 调用。这种方法永远不会可靠。）

例如，

线程 1 打印一行，告诉线程 2 - "your turn"，然后等待轮到它
线程 2 打印一行，告诉线程 3 - "your turn"，然后等待轮到它
线程 3 打印一行，告诉线程 1 - "your turn"，然后等待轮到它
等等

直到你走到尽头。（然后你需要做一些特别的事情......）

对于每三对线程，此通知可以采用 3 个单独的 "channels"（原始互斥锁、锁存器、信号量、队列等）形式，或者每个线程等待的单个 "channel"轮到它了。

（还有其他方法可以解决这个问题......但我们不需要在这里讨论。）

如何使多个线程运行并行执行，以便一个接一个地执行线程

How to make multiple threads run parallally such that execution of threads takes place one after the other

java

concurrency

multithreading

threadpool

如何使多个线程 运行 并行执行，以便一个接一个地执行线程

How to make multiple threads run parallally such that execution of threads takes place one after the other

java

concurrency

multithreading

threadpool

如何使多个线程运行并行执行，以便一个接一个地执行线程