Java：当线程池中的所有线程都完成时，通知主类/不同线程中对象的相同实例 [英] Java: notify main class when all threads in threadpool are finished / same instance of object in different threads

问题描述

当 ThreadPoolExecutor 中的所有线程都完成后，如何通知我的主类实例化 ThreadPoolExecutor ？ / p>

How do I notify my main class which instantiates a ThreadPoolExecutor when all threads within the ThreadPoolExecutor are completed?

ThreadPoolExecutor threadPool = null;
ThreadClass threadclass1;
ThreadClass threadclass2;
final ArrayBlockingQueue<Runnable> queue = new ArrayBlockingQueue<Runnable>(maxPoolSize);

puclic MyClass(){
        threadPool = new ThreadPoolExecutor(poolSize, maxPoolSize, keepAliveTime, TimeUnit.SECONDS, queue);

        threadClass1 = new ThreadClass;
        threadClass2 = new ThreadClass;

        threadPool.execute(threadClass1);
        threadPool.execute(threadClass2);

        //Now I would like to do something until the threadPool is done working
        //The threads fill a ConcurrentLinkedQueueand I would like to poll
        //the queue as it gets filled by the threads and output 
        //it to XML via JAX-RS

}

编辑1

我的线程从某处获取数据并将此信息填入ConcurrentLinkedQueue我基本上想在MyClass中执行一些操作来更新带有结果的XML输出。当所有线程都被终止时，我想返回真实的JAX-RS webservice，它实例化了MyClass，因此webservice知道所有数据已被提取，现在它可以显示最终的XML文件

EDIT 1

Wile my threads fetch data from somewhere and fill this information into a ConcurrentLinkedQueue I basically would like to perform some action in MyClass to update the XML output with the results. When all threads are terminated I would like to return true to the JAX-RS webservice which instantiated MyClass so the webservice knows all data has been fetched and it can now display the final XML file

我将 Queue 传递给线程，以便他们可以将项目添加到队列中。当一个驱动程序完成后，将项目添加到 articleQueue 我想在我的主类中执行操作，轮询实体从队列并将其交给响应对象以某种方式显示它。

I am passing a Queue to threads so they can add items to the queue. When one driver is done adding items to the articleQueue I want to perform an action within my main class, polling the entity from the Queue and handing it over to the response object to display it in some way.

当我将队列传递给线程时，它们是使用相同的对象还是使用对象的副本，以便线程内的更改不会影响主对象？那不是我想要的行为。当我在驱动程序中检查 articleQueue 的大小时，它是 18 ， DriverController 中 articleQueue 的大小为 0 。

When I pass the queue to the threads, are they working with the same object or with a "copy" of the object so that changes within the thread do not effect the main object? That is not the behavior I want. When I check the size of the articleQueue within the Driver it is 18, the size of the articleQueue in the DriverController is 0.

当一个线程在我的while循环之外的队列中添加了一些内容时，是否有更好的方法做出反应？如何修改我的代码以访问不同类中的同一对象？

Is there a nicer way to react when a thread has added something to the queue other than my while loop? How do I have to modify my code to acces the same object within different classes?

public class DriverController {

    Queue<Article> articleQueue;

    ThreadPoolExecutor threadPool = null;
    final ArrayBlockingQueue<Runnable> queue = new ArrayBlockingQueue<Runnable>(
            maxPoolSize);

    public DriverController(Response response) {

        articleQueue = new ConcurrentLinkedQueue<Article>();
        threadPool = new ThreadPoolExecutor();
        Driver driver = new Driver(this.articleQueue);

        threadPool.execute(driver);
        // More drivers would be executed here which add to the queue

        while (threadPool.getActiveCount() > 0) {
            // this.articleQueue.size() gives back 0 here ... why?
            if(articleQueue.size()>0){
                response.addArticle(articleQueue.poll());
            }
        }

    }
}

驱动程序

Driver

public class Driver implements Runnable{

    private Queue<Article> articleQueue;

    public DriverAlliedElectronics(Queue articleQueue) {
        this.articleQueue = articleQueue;
    }

    public boolean getData() {
        // Here would be the code where the article is created ...

        this.articleQueue.offer(article);
        return true;
    }

    public void run() {
        this.getData();
        // this.articleQueue.size() gives back 18 here ...

    }
}

推荐答案

也许 ExecutorCompletionService 可能适合你：

http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ExecutorCompletionService.html

上面链接中的示例：

void solve(Executor e, Collection<Callable<Result>> solvers)
  throws InterruptedException, ExecutionException {
    CompletionService<Result> ecs = new ExecutorCompletionService<Result>(e);
    for (Callable<Result> s : solvers)
        ecs.submit(s);
    int n = solvers.size();
    for (int i = 0; i < n; ++i) {
        Result r = ecs.take().get();
        if (r != null) 
            use(r);
    }
}

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