获取synchronized锁中的阻塞队列中的线程是非公平的

最新推荐文章于 2024-06-06 10:40:40 发布

weixin_33739523

最新推荐文章于 2024-06-06 10:40:40 发布

阅读量62

点赞数

CC 4.0 BY-SA版权

文章标签： java

原文链接：http://www.cnblogs.com/softidea/p/5530798.html

本文通过一个简单的Java示例程序演示了synchronized关键字在阻塞队列中的使用情况，并展示了多个线程如何竞争同一锁资源的过程。实验结果显示，线程获取锁的机会并不公平。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

synchronized中阻塞队列的线程是非公平的

测试demo:

import java.text.MessageFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.TimeUnit;

public class SleepState {

    public static ThreadLocal<SimpleDateFormat> threadLocal = new ThreadLocal<SimpleDateFormat>() {
        @Override
        protected SimpleDateFormat initialValue() {
            return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSZ");
        }
    };

    private static final int[] lock = new int[0];

    public static void main(String[] args) throws InterruptedException {
        Thread thread1 = new Thread(new TestSynchronizedTask(lock, 1000 * 10), "Thread1");
        Thread thread2 = new Thread(new TestSynchronizedTask(lock, 10), "Thread2");
        Thread thread3 = new Thread(new TestSynchronizedTask(lock, 1000), "Thread3");
        thread1.start();
        TimeUnit.MILLISECONDS.sleep(1000);
        thread2.start();
        TimeUnit.MILLISECONDS.sleep(1000);
        thread3.start();
    }
}

class TestSynchronizedTask implements Runnable {
    private final int[] lock;
    private int sleepMilliSeconds;

    public TestSynchronizedTask(int[] lock, int sleepMilliSeconds) {
        this.lock = lock;
        this.sleepMilliSeconds = sleepMilliSeconds;
    }

    public TestSynchronizedTask(int[] lock) {
        this(lock, 0);
    }

    @Override
    public void run() {
        synchronized (lock) {
            try {
                System.out.println(MessageFormat.format(" {0} {1}  begin", SleepState.threadLocal.get().format(new Date()), Thread.currentThread()));
                TimeUnit.MILLISECONDS.sleep(sleepMilliSeconds);
                System.out.println(MessageFormat.format("{0} {1}  will end", SleepState.threadLocal.get().format(new Date()), Thread.currentThread()));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

执行结果：
 2016-05-26 13:31:44.260+0800 Thread[Thread1,5,main]  begin
2016-05-26 13:31:54.260+0800 Thread[Thread1,5,main]  will end
 2016-05-26 13:31:54.260+0800 Thread[Thread3,5,main]  begin
2016-05-26 13:31:55.260+0800 Thread[Thread3,5,main]  will end
 2016-05-26 13:31:55.260+0800 Thread[Thread2,5,main]  begin
2016-05-26 13:31:55.276+0800 Thread[Thread2,5,main]  will end

转载于:https://www.cnblogs.com/softidea/p/5530798.html