如果群集中的第一个节点已关闭，Redis客户端（Redission）将停止工作

Question

I have a Master Master redis cluster of 3 (node1,node2,node3). I'm using a Redission client for distributed locking across JVM. Now according to the RedLock algorithm which is implemented by Redission it tries to acquire lock in majority of the nodes(In my case 2 is the majority) and it uses round robin algorithm for load balancing. Now this locking mechanism works fine if we block the network for node2 or node 3. But if we block node1's network then it fails with the below error

Exception in thread "main" org.redisson.client.RedisNodeNotFoundException: No node for slot: 15087 and command (EVAL)
at org.redisson.connection.MasterSlaveConnectionManager.getEntry(MasterSlaveConnectionManager.java:578)
at org.redisson.connection.MasterSlaveConnectionManager.connectionWriteOp(MasterSlaveConnectionManager.java:563)
at org.redisson.command.CommandAsyncService.async(CommandAsyncService.java:368)
at org.redisson.command.CommandAsyncService.evalAsync(CommandAsyncService.java:334)
at org.redisson.command.CommandAsyncService.evalWriteAsync(CommandAsyncService.java:282)
at org.redisson.RedissonLock.tryLockInnerAsync(RedissonLock.java:207)
at org.redisson.RedissonLock.tryAcquire(RedissonLock.java:139)
at org.redisson.RedissonLock.tryLock(RedissonLock.java:225)
at com.seamless.common.cache.distributed.LockManager.getLock(LockManager.java:37)
at com.testlock.app.App.main(App.java:34)

Below is how I'm creating the Redission client

    import java.util.List;
import java.util.concurrent.TimeUnit;

import org.apache.log4j.Logger;
import org.redisson.ClusterServersConfig;
import org.redisson.Config;
import org.redisson.ReadMode;
import org.redisson.Redisson;
import org.redisson.RedissonClient;
import org.redisson.core.RLock;

public class LockManager {


private static final Logger LOG = Logger.getLogger(LockManager.class);


private RedissonClient redissonClient;

LockManager(List<String> nodes){
    Config config = new Config();
    ClusterServersConfig serverConfig=config.useClusterServers();
    serverConfig.setReadMode(ReadMode.MASTER);
    for(String node :nodes){
        serverConfig.addNodeAddress(node);
    }
    redissonClient = Redisson.create(config);

}

public boolean getLock(final String lockKey,int timeout){
    RLock lock=redissonClient.getLock(lockKey);
    try {
        return lock.tryLock(0, timeout, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
        LOG.error("Error getting lock "+e.getMessage());
    }
    return false;
}   

public void releaseLock(final String lockKey){
    RLock lock=redissonClient.getLock(lockKey);
    if(lock.isHeldByCurrentThread())
        lock.unlock();
}
}

Answer 1

You have to use RedissonRedLock and 3 locks for RedLock algorithm:

RLock lock1 = redisson.getLock("lock1");
RLock lock2 = redisson.getLock("lock2");
RLock lock3 = redisson.getLock("lock3");

RedissonRedLock lock = new RedissonRedLock(lock1, lock2, lock3);
lock.lock();

//...

lock.unlock();