java - LinkedBlockingQueue 阻塞问题

Question

当用LinkedBlockingQueue的take()方法获取队列信息时

一旦队列为空，则进入阻塞状态

再往队列里put()元素，take()方法会自动获取新加入元素，还是始终保持阻塞状态？

Answer 1

Automatic acquisition, no blocking

Answer 2

If it is still blocking, what is the use of this class?

Answer 3

It is recommended to look at the source code and you will know, it is very beneficial

Answer 4

@wxmimperio The answer you adopted is wrong. ConcurrentLinkedQueue is non-blocking, and LinkedBlockingQueue is blocking. I will give you the codes respectively: as follows:

import java.util.concurrent.LinkedBlockingQueue;
public class TestLinkedBlockingQueue {
    public static void main(String[] args) {
        LinkedBlockingQueue<String> queue = new LinkedBlockingQueue<String>();
        try {
            queue.put("a");
            queue.put("b");
            System.out.println(queue.take());
            System.out.println(queue.take());
            System.out.println(queue.take());
            queue.put("c");
            System.out.println(queue.take());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
//输出结果：
//a
//b

But look at the non-blocking ConcurrentLinkedQueue

import java.util.concurrent.ConcurrentLinkedQueue;
public class TestConcurrentLinkedQueue {
    public static void main(String[] args) {
        ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<String>();
        queue.add("a");
        queue.add("b");
        System.out.println(queue.peek());
        queue.remove();
        System.out.println(queue.peek());
        queue.remove();
        System.out.println(queue.peek());
        queue.remove();
        queue.add("c");
        System.out.println(queue.peek());
        queue.remove();
    }
}
//a
//b
//null
//Exception in thread "main" java.util.NoSuchElementException
//    at java.util.AbstractQueue.remove(AbstractQueue.java:117)
//    at TestConcurrentLinkedQueue.main(TestConcurrentLinkedQueue.java:14)