Tonight I’ve sussed out the thread pooling in Java. I wanted a way of being able to queue up threads to be run, but I also wanted to allow the execution of so many threads at a time in this pool. I’ve heard about these thread pools but as of yet, not used them. I need something like this for my own project for both the server and the client.

package threadpooltest;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ThreadPoolTest {

    public static void main(String[] args) {
        ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(5);
        
        for (int i = 0; i <= 8; i++)
        {
            WorkerTest task = new WorkerTest("Task " + i);
            System.out.println("A new task has been added : " + task.getName());
            executor.execute(task);
        }
        
        System.out.println("Main thread sleeping");
        try { Thread.sleep(8000); } 
        catch (InterruptedException ex) {}
        System.out.println("Finished sleeping");
        
        for (int i = 0; i <= 10; i++)
        {
            WorkerTest task = new WorkerTest("Task " + (i + 5));
            System.out.println("A new task has been added : " + task.getName());
            executor.execute(task);
        }
        
        // THIS DOESN'T WORK
        //System.out.println("WAITING FOR TASKS TO FINISH");
        //try { executor.awaitTermination(1, TimeUnit.DAYS); } 
        //catch (InterruptedException ex) {}
        //System.out.println("FINISHED");
        
        executor.shutdown();
    }
    
}

No proper code snippet plugin yet! Grrr!

Anyway, the above code creates the thread pool which will run a max of 5 threads and queue the rest up. Just what I wanted.

package threadpooltest;

import java.util.concurrent.TimeUnit;

public class WorkerTest implements Runnable {

    private String name;
    
    public WorkerTest(String name) {
        this.name = name;
    }
    
    public String getName() {
        return name;
    }
    
    @Override
    public void run() {
        try
        {
            Long duration = (long) (Math.random() * 5);
            System.out.println("Start Task: " + name);
            TimeUnit.SECONDS.sleep(duration);
            System.out.println("Finished Task: " + name);
        }
        catch (InterruptedException e) {}
    }
}

The above is the example thread I was testing this with.

All I need now is to do the same with C++, but I’ve already found a header only project on github that does just that.

More to come…

EDIT:

I’ve also noted that the above works on Android too.

At the moment, I’m not holding my breath to see it this works with GWT.

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