消费者生产者错误中的意外输出

Question

我得到了一个代码，我正在尝试运行它给出了意外的输出。

代码：

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ProducerConsumerBlockingQueue {

    public static void main(String[] args) {
        Buffer buffer = new Buffer();

        ExecutorService executor = Executors.newFixedThreadPool(2);
        executor.execute(new ProdBlock(buffer));
        executor.execute(new ConsBlock(buffer));
        executor.shutdown();
    }

}
class ProdBlock implements Runnable{

    Buffer buffer;
    public ProdBlock(Buffer buffer) {
        this.buffer = buffer;
    }

    public void run() {
        for(int i = 1; i <= 10; i++){
            buffer.put(i);
        }

    }

}
class ConsBlock implements Runnable{

    Buffer buffer;
    ConsBlock(Buffer buffer){
        this.buffer = buffer;
    }
    public void run() {
        for(int i = 1; i <= 10; i++){
            buffer.get();
        }       
    }

}
class Buffer{
    int i;
    BlockingQueue<Integer> sharedObject = new ArrayBlockingQueue<Integer>(1);

    public void get(){
        try {
            System.out.println("Getting - " + sharedObject.take());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    public void put(int i){
        this.i = i;
        try {
            sharedObject.put(i);
            System.out.println("Putting - " + i);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

输出：

Putting - 1
Putting - 2
Getting - 1
Putting - 3
Getting - 2
Getting - 3
Putting - 4
Putting - 5
Getting - 4
Getting - 5
Putting - 6
Getting - 6
Putting - 7
Putting - 8
Getting - 7
Getting - 8
Putting - 9
Putting - 10
Getting - 9
Getting - 10

预期输出：

Putting - 1
Getting - 1
Putting - 2
Getting - 2
Putting - 3
Getting - 3
Putting - 4
Getting - 4
Putting - 5
Getting - 5
Putting - 6
Getting - 6
Putting - 7
Getting - 7
Putting - 8
Getting - 8
Putting - 9
Getting - 9
Putting - 10
Getting - 10

正如预期的那样，阻塞队列一次应该只取 1 个值，它是如何存储多个值的？

Answer 1

它没有存储多个值。只是一旦 take() 方法已经返回，生产者可以在其他线程打印取值之前向队列添加一个值并打印它：

生产者线程：调用 put(1) - 队列有 1 个元素
生产者线程：打印"Putting 1" - 队列有 1 个元素
消费者线程：调用 take() - 队列为空
生产者线程：调用 put(2) - 队列有 1 个元素
生产者线程：打印"Putting 2" - 队列有 1 个元素
消费者线程：将字符串"Getting - "与第3步得到的整数1拼接，打印结果——队列有1个元素

消费者生产者错误中的意外输出

Unexpected output in Consumer Producer error

java

blockingqueue