以生产者/消费者模式挂起消费者 [英] Suspend consumer in producer/consumer pattern

问题描述

我将生产者和消费者与BlockingQueue相关联.

I have producer and consumer connected with BlockingQueue.

消费者等待队列中的记录并对其进行处理:

Consumer wait records from queue and process it:

Record r = mQueue.take();
process(r);

我需要从其他线程暂停此过程一段时间.如何实施?

I need pause this process for a while from other thread. How to implement it?

现在我认为可以实现它，但这似乎是一个糟糕的解决方案:

Now I think implement it such, but it's looks like bad solution:

private Object mLock = new Object();
private boolean mLocked = false;

public void lock() {
    mLocked = true;
}

public void unlock() {
    mLocked = false;
    mLock.notify();

}

public void run() {
    ....
            Record r = mQueue.take();
            if (mLocked) {
                mLock.wait();
            }
            process(r);
}

推荐答案

我认为您的解决方案简单而优雅，并且您应该对其进行一些修改.我建议的修改是同步.

I think your solution is simple and elegant, and think you should keep it with some modifications. The modifications I propose are synchronization.

没有它，可能会(并且经常)发生线程干扰和内存一致性错误.最重要的是，您不能wait或notify放在您不拥有的锁上(如果您在synchronized块中拥有它，则可以拥有它.)修复很容易，只需在您等待/通知的位置添加mLock同步块.另外，当您从其他线程更改mLocked时，您将需要对其进行标记 volatile .

Without it, thread interference and memory consistancy errors can (and very often does) occur. On top of that, you can't wait or notify on a lock you don't own (and you own it if you have it inside a synchronized block..). The fix is easy, just add a mLock synchronize block where you wait/notify on it. Also, as you're changing mLocked from a different thread you will want to mark it volatile.

private Object mLock = new Object();
private volatile boolean mLocked = false;

public void lock() {
    mLocked = true;
}

public void unlock() {
    synchronized(mlock) {
        mLocked = false;
        mLock.notify();
    }

}

public void run() {
    ....
            Record r = mQueue.take();
            synchronized(mLock) {
                while (mLocked) {
                    mLock.wait();
                }
            }
            process(r);
}

这篇关于以生产者/消费者模式挂起消费者的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！