6.redis集羣

    考慮到互聯網使用環境極其複雜，需要高效穩定的redis環境，redis3.0增加了cluster功能，可以給redis集羣部署，這樣的好處是性能穩定，但是缺點是非常重，運營不方便，並且至少需要部署6個節點，而且有坑。

   下面轉載了一個同學的文章來搭建集羣部署環境，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);  
        //創建節點
        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);  
  
        // 超時，最大的轉發數，最大鏈接數，最小鏈接數都會影響到集羣  
        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");
            }
        }
    }

}

創建一個JedisCluster，JedisCluster封裝了redis的命令，這樣就可以直接調用操作redis。測試的qps大概4萬左右，和ShardedJedisPool差不多，存儲100個數，可能節點1、5一樣，2、4的一樣，但是每一個節點的數據都不會超過100個，按一種算法去算，當一個節點掛了，並不會影響程序的正常使用，當剩下2個節點後，程序會報錯，這樣保證了高可用高併發性。