队列完全错误,与多个消费者,生产者合作

Question

我想模拟以下场景:多个使用者,生产者线程正在修改一些数据

建立

    BlockingQueue<String> q1 = new SynchronousQueue<String>();
    BlockingQueue<String> q2 = new SynchronousQueue<String>();

    Producer dataProducer = new Producer(q1); // publish to q1

    Filter1 filter1 = new Filter1(q1, q2);    // read from q1, publish to q2
    Filter2 filter2 = new Filter2(q2);        // read from q2

    new Thread(dataProducer, "Producer-Thread").start();
    new Thread(filter1, "Filter1-Thread").start();
    new Thread(filter2, "Filter2-Thread").start();

制片人

public void run() {
    try {
        while (true) {
            this.q.put(saySomething());
        }
    } catch (InterruptedException ex) {
        ex.printStackTrace();
    }
}

public String saySomething() {
    return "Something";
}

过滤1

public void run() {
    try {
        while (true) {
            consume(qIn.take());
        }
    } catch (InterruptedException ex) {
        ex.printStackTrace();
    }
}

private void consume(String take) {
    //Modify data according to some rules
    String newData = take.replace("m", "-");
    produce(newData);
}

private void produce(String newData) {
    // put new data in queue out
    qOut.add(newData);                   // <-- Stacktrace points here
}

过滤2

public void run() {
    try {
        while (true) {
            consume(qIn.take());
        }
    } catch (InterruptedException ex) {
        ex.printStackTrace();
    }
}

private void consume(String s) {
    System.out.println("Something became: " + s);
}

因此,回顾一下:Producer将一些内容放入Filter 1读取的队列中.它修改数据并将其发布到Filter 2读取的另一个队列.过滤器2打印最终数据.

此代码失败

Exception in thread "Thread-2" java.lang.IllegalStateException: Queue full

你能帮我理解为什么吗？

Answer 1

你应该使用put()而不是add()A SynchronousQueue总是满和空,它没有深度.put()将告诉队列暂停此线程,直到另一个线程进入以从队列中取出该元素.

add()只有在线程等待时,该方法才会成功,如果没有线程在等待,您将获得Queue Full异常.