分布式锁的应用

之前说到redis队列的场景使用lua脚本可以解决高并发的原子性问题，但是redis集群并不支持lua脚本，因此想要实现原子性防止高并发的问题就需要使用分布式锁。

        这里总结两种分布式锁的实现，使用Redisson和Zookeeper。

一、场景回顾

先回顾一下场景，我们假设两个线程分别为不同jvm上的两个程序，一个服务在入队，一个服务在出队，看看判断入队的逻辑是否可靠

public static void main(String[] args) {CountDownLatch countDownLatch = new CountDownLatch(1);LockTest lockTest = new LockTest();Runnable inQueue = ()->{for(int i=0; i<100; i++) {try {lockTest.inQueue(i);countDownLatch.countDown();} catch (Exception e) {e.printStackTrace();}}};Runnable outQueue = ()->{try {countDownLatch.await();for(int i=0; i<30; i++) {lockTest.outQueue();}} catch (Exception e) {e.printStackTrace();}};new Thread(inQueue).start();new Thread(outQueue).start();}

public class LockTest {private ReentrantLock lock = new ReentrantLock();public void inQueueWithScript(int value) {System.out.println(Thread.currentThread().getName()+" inQueue");long success = (long) JedisUtil.evalScript(LuaSysContants.IN_QUEUE.getName(), LuaSysContants.IN_QUEUE.getScript(), 1, "result_list", String.valueOf(value));if(success == 0) {System.err.println("入队出错！");}}public void inQueue(int value) {System.out.println(Thread.currentThread().getName()+" rpush");long retValue = JedisUtil.rpush("result_list", String.valueOf(value));System.out.println(Thread.currentThread().getName()+" llen");long len = JedisUtil.llen("result_list");if(retValue != len) {System.err.println(retValue+":"+len);System.err.println("入队出错！");}}public void outQueue() {System.out.println(Thread.currentThread().getName()+" lpop");JedisUtil.lpop("result_list");}}

我们发现，很可能会出现判断出错的情况

二、Redisson实现分布式锁

我们使用Redisson加锁，可以解决这个问题

Redisson工具类

public class RedissonUtil {private static Config config = new Config();    private static Redisson redisson = null;    // 不要在分布式环境里用静态块初始化配置    public static void init(){        try {//            config.useClusterServers() //这是用的集群server//                    .setScanInterval(2000) //设置集群状态扫描时间//                    .setMasterConnectionPoolSize(200) //设置连接数//                    .setSlaveConnectionPoolSize(300)//                    dev//                    .addNodeAddress("redis://@127.0.0.1:6379");//                    product//                    .addNodeAddress("redis://@120.76.194.117:6379");                        config.useSingleServer()              .setConnectionPoolSize(200)              .setAddress("redis://@127.0.0.1:6379")              .setPassword("123456");                          redisson = (Redisson) Redisson.create(config);            System.out.println(redisson);        }catch (Exception e){            e.printStackTrace();        }    }        public static Redisson getRedisson(){        return redisson;    }        public static <V> RDeque<V> getRDeque(String key){          RDeque<V> rDeque=redisson.getDeque(key);          return rDeque;      }      }

分布式锁工具类

public class DistributedRedisLock {private static Logger logger = Logger.getLogger(DistributedRedisLock.class.getName());private static final String LOCK_TITLE = "lock_";public static void acquire(String lockName){Redisson redisson = RedissonUtil.getRedisson();logger.log(Level.INFO, "加分布式锁:" + LOCK_TITLE + lockName);                String key = LOCK_TITLE + lockName;                RLock mylock = redisson.getLock(key);                mylock.lock(2, TimeUnit.MINUTES);                 logger.log(Level.INFO, "加分布式锁成功:" + LOCK_TITLE + lockName);       }public static boolean acquireFaileToBreak(String lockName){Redisson redisson = RedissonUtil.getRedisson();logger.log(Level.INFO, "加分布式锁:" + LOCK_TITLE + lockName);                String key = LOCK_TITLE + lockName;                RLock mylock = redisson.getLock(key);                if(mylock.isLocked()) {           return false;                }                mylock.lock(2, TimeUnit.MINUTES);                 logger.log(Level.INFO, "加分布式锁成功:" + LOCK_TITLE + lockName);                return true;        }public static void release(String lockName){Redisson redisson = RedissonUtil.getRedisson();logger.log(Level.INFO, "释放分布式锁:" + LOCK_TITLE + lockName);                String key = LOCK_TITLE + lockName;                RLock mylock = redisson.getLock(key);                mylock.unlock();                logger.log(Level.INFO, "释放分布式锁成功:" + LOCK_TITLE + lockName);       }}

public static void main(String[] args) {CountDownLatch countDownLatch = new CountDownLatch(1);RedissonUtil.init();JedisUtil jedisUtil = new JedisUtil();LockTest lockTest = new LockTest();Runnable inQueue = ()->{for(int i=0; i<100; i++) {try {lockTest.inQueue(i);countDownLatch.countDown();} catch (Exception e) {e.printStackTrace();}}};Runnable outQueue = ()->{try {countDownLatch.await();for(int i=0; i<30; i++) {lockTest.outQueue();}} catch (Exception e) {e.printStackTrace();}};new Thread(inQueue).start();new Thread(outQueue).start();}

public class LockTest {private ReentrantLock lock = new ReentrantLock();public void inQueueWithScript(int value) {System.out.println(Thread.currentThread().getName()+" inQueue");long success = (long) JedisUtil.evalScript(LuaSysContants.IN_QUEUE.getName(), LuaSysContants.IN_QUEUE.getScript(), 1, "result_list", String.valueOf(value));if(success == 0) {System.err.println("入队出错！");}}public void inQueue(int value) {// 分布式Redisson锁DistributedRedisLock.acquire("lock");try {System.out.println(Thread.currentThread().getName()+" rpush");long retValue = JedisUtil.rpush("result_list", String.valueOf(value));System.out.println(Thread.currentThread().getName()+" llen");long len = JedisUtil.llen("result_list");if(retValue != len) {System.err.println(retValue+":"+len);System.err.println("入队出错！");}} finally {DistributedRedisLock.release("lock");}}public void outQueue() {// 分布式Redisson锁DistributedRedisLock.acquire("lock");try {System.out.println(Thread.currentThread().getName()+" lpop");JedisUtil.lpop("result_list");} finally {DistributedRedisLock.release("lock");}}}

    三、Zookeeper实现分布式锁

分布式锁工具类

public class DistributedZookeepLock {private static Logger logger = Logger.getLogger(DistributedZookeepLock.class.getName());public static final CuratorFramework client = CuratorFrameworkFactory.builder()     .connectString("127.0.0.1:2181")     .retryPolicy(new ExponentialBackoffRetry(1000,3)).build();public static InterProcessMutex acquire(String lockPath) throws Exception{if(client.getState() != CuratorFrameworkState.STARTED) {client.start();}logger.log(Level.INFO, "加分布式锁:" + lockPath);InterProcessMutex lock = new InterProcessMutex(client, lockPath);lock.acquire();logger.log(Level.INFO, "加分布式锁成功:" + lockPath);return lock;}public static void release(InterProcessMutex lock) throws Exception{if(client.getState() != CuratorFrameworkState.STARTED){System.out.println(Thread.currentThread().getName()+" release start");client.start();}logger.log(Level.INFO, "释放分布式锁");lock.release();logger.log(Level.INFO, "释放分布式锁成功");}}

public class LockTest {private ReentrantLock lock = new ReentrantLock();public void inQueueWithScript(int value) {System.out.println(Thread.currentThread().getName()+" inQueue");long success = (long) JedisUtil.evalScript(LuaSysContants.IN_QUEUE.getName(), LuaSysContants.IN_QUEUE.getScript(), 1, "result_list", String.valueOf(value));if(success == 0) {System.err.println("入队出错！");}}public void inQueue(int value) {// 分布式zookeeper锁InterProcessMutex lock = null;try {lock = DistributedZookeepLock.acquire("/lock");} catch (Exception e) {e.printStackTrace();}try {System.out.println(Thread.currentThread().getName()+" rpush");long retValue = JedisUtil.rpush("result_list", String.valueOf(value));System.out.println(Thread.currentThread().getName()+" llen");long len = JedisUtil.llen("result_list");if(retValue != len) {System.err.println(retValue+":"+len);System.err.println("入队出错！");}} finally {try {DistributedZookeepLock.release(lock);} catch (Exception e) {e.printStackTrace();}}}public void outQueue() {// 分布式zookeeper锁InterProcessMutex lock = null;try {lock = DistributedZookeepLock.acquire("/lock");} catch (Exception e) {e.printStackTrace();}try {System.out.println(Thread.currentThread().getName()+" lpop");JedisUtil.lpop("result_list");} finally {try {DistributedZookeepLock.release(lock);} catch (Exception e) {e.printStackTrace();}}}}

public static void main(String[] args) {CountDownLatch countDownLatch = new CountDownLatch(1);JedisUtil jedisUtil = new JedisUtil();LockTest lockTest = new LockTest();Runnable inQueue = ()->{for(int i=0; i<100; i++) {try {lockTest.inQueue(i);countDownLatch.countDown();} catch (Exception e) {e.printStackTrace();}}};Runnable outQueue = ()->{try {countDownLatch.await();for(int i=0; i<30; i++) {lockTest.outQueue();}} catch (Exception e) {e.printStackTrace();}};new Thread(inQueue).start();new Thread(outQueue).start();}