SynchronousQueue 小demo

最新推荐文章于 2020-07-30 22:10:53 发布

原创最新推荐文章于 2020-07-30 22:10:53 发布 · 437 阅读

CC 4.0 BY-SA版权

本文通过实战演示了 Java 中 SynchronousQueue 的工作原理。代码示例展示了如何利用 ExecutorService 和 SynchronousQueue 进行线程间的同步操作。具体讨论了插入操作与移除操作之间的依赖关系，以及这种依赖如何影响线程的行为。

代码1：

package com.zkk;

import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;

public class Test4 {
	public static void main(String[] args) {
		final SynchronousQueue<String> syn = new SynchronousQueue<String>();
		ExecutorService threadPool = Executors.newCachedThreadPool();
		for (int i = 0; i < 3; i++) {
			Runnable runn = new Runnable() {
				@Override
				public void run() {
					try {
						Thread.sleep(new Random().nextInt(1000));
						syn.put("a");
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			};
			threadPool.execute(runn);
		}
	}
}

以上的代码不会打印任何东西。

文档原话:其中每个插入操作必须等待另一个线程的对应移除操作

package com.zkk;

import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;

public class Test4 {
	public static void main(String[] args) {
		final SynchronousQueue<String> syn = new SynchronousQueue<String>();
		ExecutorService threadPool = Executors.newCachedThreadPool();
		for (int i = 0; i < 3; i++) {
			final int task=i;
			Runnable runn = new Runnable() {
				@Override
				public void run() {
					try {
						System.out.println("aa");
						Thread.sleep(new Random().nextInt(1000));
						syn.put("a"+task);
						System.out.println("bb");
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			};
			threadPool.execute(runn);
		}
		try {
			String take1 = syn.take();
			System.out.println("take1:"+take1);
			String take2 = syn.take();
			System.out.println("take2:"+take2);
			String take3 = syn.take();
			System.out.println("take3"+take3);
			String take4 = syn.take();
			System.out.println("take4:"+take4);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

以上代码打印结果:

aa
aa
aa
take1:a0
bb
bb
take2:a2
bb
take3a1

充分说明了这一点
而BlockingQueue 这没有文档这点