6.redis集群

考虑到互联网使用环境极其复杂，需要高效稳定的redis环境，redis3.0增加了cluster功能，可以给redis集群部署，这样的好处是性能稳定，但是缺点是非常重，运营不方便，并且至少需要部署6个节点，而且有坑。

下面转载了一个同学的文章来搭建集群部署环境，http://www.cnblogs.com/Xrinehart/p/3502213.html。

import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import redis.clients.jedis.HostAndPort;
import redis.clients.jedis.JedisCluster;
import redis.clients.jedis.JedisPoolConfig;

public class redisClusterConcurrent {
private static JedisCluster jedisCluster;

void init() {
JedisPoolConfig config = new JedisPoolConfig();
config.setMaxTotal(20);
config.setMaxIdle(2);
//创建节点
HostAndPort hp0 = new HostAndPort("192.168.21.171", 7000);
HostAndPort hp1 = new HostAndPort("192.168.21.171", 7001);
HostAndPort hp2 = new HostAndPort("192.168.21.171", 7002);
HostAndPort hp3 = new HostAndPort("192.168.21.171", 7003);
HostAndPort hp4 = new HostAndPort("192.168.21.171", 7004);
HostAndPort hp5 = new HostAndPort("192.168.21.171", 7005);

Set<HostAndPort> hps = new HashSet<HostAndPort>();
hps.add(hp0);
hps.add(hp1);
hps.add(hp2);
hps.add(hp3);
hps.add(hp4);
hps.add(hp5);

// 超时，最大的转发数，最大链接数，最小链接数都会影响到集群
jedisCluster = new JedisCluster(hps, 5000, 10, config);
}

public static void main(String[] args) throws InterruptedException {
final redisClusterConcurrent redisConcurrent = new redisClusterConcurrent();
redisConcurrent.init();
final AtomicLong counter = new AtomicLong(0);
final AtomicBoolean stopFlag = new AtomicBoolean(false);
final int threadCount = 1000;

for (int i = 0; i < threadCount; i++) {
final String sss = i + "";
new Thread(new Runnable() {
@Override
public void run() {
while (!stopFlag.get()) {
jedisCluster.set(sss, "aaasasdasdasdasdasdasdasdasdasdasdasdasdasaaaaaaaaaaaaaaaaaa");
counter.incrementAndGet();
}
}
}).start();

}

Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
System.err.println("*** stop client ***");
stopFlag.set(true);
}
});

long startTime = System.currentTimeMillis();
while (!stopFlag.get()) {
Thread.sleep(1000);

final long count = counter.get();
long currentTime = System.currentTimeMillis();
long qps = count * 1000 / (currentTime - startTime);
System.out.println("qps=" + qps);

if ((currentTime - startTime) / 1000 > 10) {
counter.set(0);
startTime = currentTime;
System.out.println("reset counter");
}
}
}

}

创建一个JedisCluster，JedisCluster封装了redis的命令，这样就可以直接调用操作redis。测试的qps大概4万左右，和ShardedJedisPool差不多，存储100个数，可能节点1、5一样，2、4的一样，但是每一个节点的数据都不会超过100个，按一种算法去算，当一个节点挂了，并不会影响程序的正常使用，当剩下2个节点后，程序会报错，这样保证了高可用高并发性。