Redis——SpringBoot項目使用Lettuce和Jedis接入Redis集群

Jedis連接Redis：

非線程安全

如果是多線程環境下共用一個Jedis連接池，會產生線程安全問題，可以通過創建多個Jedis實例來解決，但是創建許多socket會影響性能，因此好一點的方法是使用JedisPool

https://blog.csdn.net/lihao21/article/details/46830553

https://www.jianshu.com/p/5e4a1f92c88f

為什么 jedis不是線程安全的，可以通過一個demo來說明：

public class BadConcurrentJedisTest {

    private static final ExecutorService pool = Executors.newFixedThreadPool(20); private static final Jedis jedis = new Jedis("127.0.0.1", 6379); public static void main(String[] args) { for(int i=0;i<20;i++){ pool.execute(new RedisSet()); } } static class RedisSet implements Runnable{ @Override public void run() { while(true){ jedis.set("hello", "world"); } } }

這時候后台報錯：

redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketException: Socket Closed

主要的原因就在於jedis實例中的兩個成員變量：RedisInputStream和RedisOutputStream

jedis在執行每一個命令之前都會先執行connect方法，socket是一個共享變量，在多線程的情況下可能存在：線程1執行到：

outputStream = new RedisOutputStream(socket.getOutputStream());
inputStream = new RedisInputStream(socket.getInputStream());

線程2執行到：

socket = new Socket();
socket.connect(new InetSocketAddress(host, port), connectionTimeout);

因為線程2重新初始化了socket但是還沒有執行connect，所以線程1執行socket.getOutputStream()或者socket.getInputStream()就會拋出java.net.SocketException: Socket is not connected。

Jedis解決線程安全的方式就是使用連接池：

每個線程去連接池中獲取一個Jedis實例，這樣就在有限個socket的情況下保證了線程安全

Lettuce連接Redis：

線程安全

Lettuce是基於netty的，性能比較好。

多線程使用同一連接實例時，是線程安全的。

 

application-test.yml

redis:
  nodes:
    - host1:port1
    - host2:port2

-----------------------------------------------------------------Lettuce-----------------------------------------------------------------

導入依賴：

    //Redis
    compile 'org.springframework.boot:spring-boot-starter-data-redis-reactive'

配置類：

import io.lettuce.core.RedisURI;
import io.lettuce.core.cluster.RedisClusterClient;
import io.lettuce.core.cluster.api.StatefulRedisClusterConnection;
import io.lettuce.core.cluster.api.sync.RedisClusterCommands;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.ArrayList;
import java.util.List;

@Configuration
@ConfigurationProperties(prefix = "redis")
public class LettuceConfig {
    private List<String> nodes;

    public List<String> getNodes() {
        return nodes;
    }

    public void setNodes(List<String> nodes) {
        this.nodes = nodes;
    }

    @Bean
    RedisClusterCommands<String, String> redisCommands() {
        List<RedisURI> uriList = new ArrayList<>();
        nodes.forEach(node -> {
            String[] addrStr = node.split(":");
            String host = addrStr[0];
            int port = Integer.parseInt(addrStr[1]);

            RedisURI redisUri = RedisURI.Builder.redis(host).withPort(port).build();
            uriList.add(redisUri);
        });
        RedisClusterClient redisClient = RedisClusterClient.create(uriList);
        StatefulRedisClusterConnection<String, String> connection = redisClient.connect();
        RedisClusterCommands<String, String> syncCommands = connection.sync();

        return syncCommands;
    }

}

-----------------------------------------------------------------Jedis-----------------------------------------------------------------

導入依賴：

compile group: 'redis.clients', name: 'jedis', version: '2.9.0'

配置類：

package com.youdao.outfox.interflow.config;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import redis.clients.jedis.HostAndPort;
import redis.clients.jedis.JedisCluster;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

@Configuration
@ConfigurationProperties(prefix = "redis")
public class JedisClusterConfig {

    private List<String> nodes;

    public List<String> getNodes() {
        return nodes;
    }

    public void setNodes(List<String> nodes) {
        this.nodes = nodes;
    }

    @Bean
    public JedisCluster jedisCluster() {
        Set<HostAndPort> jedisClusterNodes = new HashSet<>();
        nodes.forEach(node -> {
            String[] addrStr = node.split(":");
            String host = addrStr[0];
            int port = Integer.parseInt(addrStr[1]);
            jedisClusterNodes.add(new HostAndPort(host, port));
        });
        return new JedisCluster(jedisClusterNodes, 5, 2);
    }
}

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