zookeeper - curator

分布式锁的一个成熟框架

创建case3.CuratorLockTest用来测试练习使用框架

在pom.xml中添加依赖

<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-framework</artifactId>
    <version>4.3.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-recipes</artifactId>
    <version>4.3.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-client</artifactId>
    <version>4.3.0</version>
</dependency>

刷新pom.xml，等待依赖包下载完成。

测试类代码

public class CuratorLockTest {
    
    
    public static void main(String[] args) throws InterruptedException {
    
    
        //创建分布式锁1
        InterProcessMutex lock1 = new InterProcessMutex(getCuratorFramework(), "/lcoks");
        //创建分布式锁2
        InterProcessMutex lock2 = new InterProcessMutex(getCuratorFramework(), "/lcoks");
        new Thread(new Runnable() {
    
    
            @Override
            public void run() {
    
    
                try {
    
    
                    lock1.acquire();//获取锁
                    System.out.println("线程1 获取到锁");

                    lock1.acquire();
                    System.out.println("线程1 再次获取到锁");

                    Thread.sleep(5*1000);//线程休眠5秒钟

                    lock1.release();//释放锁
                    System.out.println("线程1 释放锁");

                    lock1.release();
                    System.out.println("线程1 再次释放锁");
                } catch (Exception e) {
    
    
                    e.printStackTrace();
                }
            }
        }).start();
        Thread.sleep(5*1000);
        new Thread(new Runnable() {
    
    
            @Override
            public void run() {
    
    
                try {
    
    
                    lock2.acquire();//获取锁
                    System.out.println("线程2 获取到锁");

                    lock2.acquire();
                    System.out.println("线程2 再次获取到锁");

                    Thread.sleep(5*1000);//线程休眠5秒钟

                    lock2.release();//释放锁
                    System.out.println("线程2 释放锁");

                    lock2.release();
                    System.out.println("线程2 再次释放锁");
                } catch (Exception e) {
    
    
                    e.printStackTrace();
                }
            }
        }).start();
    }

    private static CuratorFramework getCuratorFramework() {
    
    
        ExponentialBackoffRetry retry = new ExponentialBackoffRetry(3000, 3);//多少秒，重复次数
        CuratorFramework client = CuratorFrameworkFactory.builder().connectString("Hadoop003:2181,Hadoop004:2181,Hadoop005:2181")
                .connectionTimeoutMs(2000)
                .sessionTimeoutMs(2000)
                .retryPolicy(retry).build();
        client.start();

        System.out.println("ZooKeeper 启动成功");
        return client;

    }


}

InterProcessMutex 分布式锁类；使用时节点先获取锁 acquire，操作完成后release释放锁；其他节点便可以获取到锁。

运行后，观察到只有前一个节点释放锁后，第二个节点才能获取锁。