在并发程序中从BlockingQueue获取对象的最佳方法？

问题描述

在并发程序中，在没有达到竞态条件的情况下，从BlockingQueue中获取对象的最佳方法是什么？我目前正在做以下事情，我不相信这是最好的方法：

What is the best method to get objects out of a BlockingQueue, in a concurrent program, without hitting a race condition? I'm currently doing the following and I'm not convinced it is the best method:

BlockingQueue<Violation> vQueue;
/* 
in the constructor I pass in a BlockingQueue object 
full of violations that need to be processed - cut out for brevity
*/

Violation v;
while ( ( v = vQueue.poll(500, TimeUnit.MILLISECONDS) ) != null ) {
    // do stuff with the violation
}

我还没有达到比赛条件...但我不太确定这是否真的安全。

I have yet to hit a race condition... but, I'm none too sure if this is truly safe.

推荐答案

class Producer implements Runnable {
   private final BlockingQueue queue;
   Producer(BlockingQueue q) { queue = q; }
   public void run() {
     try {
       while (true) { queue.put(produce()); }
     } catch (InterruptedException ex) { ... handle ...}
   }
   Object produce() { ... }
 }

 class Consumer implements Runnable {
   private final BlockingQueue queue;
   Consumer(BlockingQueue q) { queue = q; }
   public void run() {
     try {
       while (true) { consume(queue.take()); }
     } catch (InterruptedException ex) { ... handle ...}
   }
   void consume(Object x) { ... }
 }

 class Setup {
   void main() {
     BlockingQueue q = new SomeQueueImplementation();
     Producer p = new Producer(q);
     Consumer c1 = new Consumer(q);
     Consumer c2 = new Consumer(q);
     new Thread(p).start();
     new Thread(c1).start();
     new Thread(c2).start();
   }
 }

此示例取自。所以你可以看到你在做正确的方式。这是告诉你它必须工作的报价：

This example was taken from the JDK 1.6 docs of BlockingQueue. So You can see that you are doing it the right way. Here's the quote which tells you that it have to work:

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