如何在ThreadPoolExecutor中访问正在运行的线程？ [英] How to access running threads inside ThreadPoolExecutor?

问题描述

我有一个运行线程的队列，并希望在执行时公开它的一些数据，以监控进程。

I have a queue of running threads and would like to expose some of its data while it is executed, to monitor the process.

ThreadPoolExecutor 提供对其队列的访问，我可以遍历这些对象来调用我重写的 toString（）方法，但这些只是等待的线程执行。

ThreadPoolExecutor provides access to its queue and I can iterate through these objects to call my overridden toString() method, but these are only threads that are waiting for execution.

有没有办法访问当前运行的线程来调用我的方法？或者也许这个任务有更好的方法吗？

Is there a way to access threads that are currently running to call my method? Or maybe there's a better approach for this task in general?

为了更清楚地说明目的，这里有一些一般性的代码：

To clarify a bit more about the purpose, here's some code of general idea:

public class GetDataTask implements Runnable {
    private String pageNumber;
    private int dataBlocksParsed;
    private String source;
    private String dataType;


    public GetDataTask(String source, String dataType) {
        this.source = source;
        this.dataType = dataType;
    }

    @Override
    public void run() {
        //do stuff that affects pageNumber and dataBlocksParsed
    }

    @Override
    public String toString() {
        return "GetDataTask{" +
            "source=" + source +
            ", dataType=" + dataType +
            ", pageNumber=" + pageNumber +
            ", dataBlocksParsed=" + dataBlocksParsed +
            '}';
    }
}

以及持有执行人的班级：

and a class holding the executor:

public class DataParseManager {
    private static ThreadPoolExecutor executor = new ThreadPoolExecutor(100, 100, 20, TimeUnit.SECONDS, new ArrayBlockingQueue<>(300));

    public void addParseDataTask(String source, String dataType) {
        executor.execute(new GetDataTask(source, dataType));
    }

    // here's the method that I need
    public String getInfo() {
        StringBuilder info = new StringBuilder();
        //and here's the method that I'm missing - executor.getActiveThreads()
        for (Runnable r : executor.getActiveThreads()) {
            info.append(((GetDataTask) r).toString()).append('\n');
        }
        return info.append(executor.toString()).toString();
   }
}

推荐答案

如何关于如此包装Runnable。

How about wrap Runnable like this.

static class MonitorRunnable implements Runnable {

    static final List<Runnable> activeTasks = Collections.synchronizedList(new ArrayList<>());

    private final Runnable runnable;

    public MonitorRunnable(Runnable runnable) {
        this.runnable = runnable;
    }

    @Override
    public void run() {
        activeTasks.add(runnable);
        runnable.run();
        activeTasks.remove(runnable);
    }
}

和

public class DataParseManager {
    private static ThreadPoolExecutor executor = new ThreadPoolExecutor(100, 100, 20, TimeUnit.SECONDS, new ArrayBlockingQueue<>(300));

    public void addParseDataTask(String source, String dataType) {
        executor.execute(new MonitorRunnable(new GetDataTask(source, dataType)));
    }

    // here's the method that I need
    public String getInfo() {
        StringBuilder info = new StringBuilder();
        //and here's the method that I'm missing - executor.getActiveThreads()
        synchronized (MonitorRunnable.activeTasks) {
            for (Runnable r : MonitorRunnable.activeTasks) {
                info.append(((GetDataTask) r).toString()).append('\n');
            }
        }
        return info.append(executor.toString()).toString();
   }
}

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