Redis的Java客户端Jedis的八种调用方式(事务、管道、分布式…)介绍

红太狼 2021-09-10 10:40 171阅读 0赞

redis是一个著名的key-value存储系统，而作为其官方推荐的java版客户端jedis也非常强大和稳定，支持事务、管道及有jedis自身实现的分布式。

在这里对jedis关于事务、管道和分布式的调用方式做一个简单的介绍和对比：

### 一、普通同步方式 ###

最简单和基础的调用方式，

@Test
    public void test1Normal() {
        Jedis jedis = new Jedis("localhost");
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            String result = jedis.set("n" + i, "n" + i);
        }
        long end = System.currentTimeMillis();
        System.out.println("Simple SET: " + ((end - start)/1000.0) + " seconds");
        jedis.disconnect();
    }

很简单吧，每次`set`之后都可以返回结果，标记是否成功。

### 二、事务方式(Transactions) ###

redis的事务很简单，他主要目的是保障，一个client发起的事务中的命令可以连续的执行，而中间不会插入其他client的命令。

看下面例子：

@Test
    public void test2Trans() {
        Jedis jedis = new Jedis("localhost");
        long start = System.currentTimeMillis();
        Transaction tx = jedis.multi();
        for (int i = 0; i < 100000; i++) {
            tx.set("t" + i, "t" + i);
        }
        List<Object> results = tx.exec();
        long end = System.currentTimeMillis();
        System.out.println("Transaction SET: " + ((end - start)/1000.0) + " seconds");
        jedis.disconnect();
    }

我们调用`jedis.watch(…)`方法来监控key，如果调用后key值发生变化，则整个事务会执行失败。另外，事务中某个操作失败，并不会回滚其他操作。这一点需要注意。还有，我们可以使用`discard()`方法来取消事务。

### 三、管道(Pipelining) ###

有时，我们需要采用异步方式，一次发送多个指令，不同步等待其返回结果。这样可以取得非常好的执行效率。这就是管道，调用方法如下：

@Test
    public void test3Pipelined() {
        Jedis jedis = new Jedis("localhost");
        Pipeline pipeline = jedis.pipelined();
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            pipeline.set("p" + i, "p" + i);
        }
        List<Object> results = pipeline.syncAndReturnAll();
        long end = System.currentTimeMillis();
        System.out.println("Pipelined SET: " + ((end - start)/1000.0) + " seconds");
        jedis.disconnect();
    }

### 四、管道中调用事务 ###

就Jedis提供的方法而言，是可以做到在管道中使用事务，其代码如下：

@Test
    public void test4combPipelineTrans() {
        jedis = new Jedis("localhost"); 
        long start = System.currentTimeMillis();
        Pipeline pipeline = jedis.pipelined();
        pipeline.multi();
        for (int i = 0; i < 100000; i++) {
            pipeline.set("" + i, "" + i);
        }
        pipeline.exec();
        List<Object> results = pipeline.syncAndReturnAll();
        long end = System.currentTimeMillis();
        System.out.println("Pipelined transaction: " + ((end - start)/1000.0) + " seconds");
        jedis.disconnect();
    }

但是经测试（见本文后续部分），发现其效率和单独使用事务差不多，甚至还略微差点。

### 五、分布式直连同步调用 ###

@Test
    public void test5shardNormal() {
        List<JedisShardInfo> shards = Arrays.asList(
                new JedisShardInfo("localhost",6379),
                new JedisShardInfo("localhost",6380));
    
        ShardedJedis sharding = new ShardedJedis(shards);
    
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            String result = sharding.set("sn" + i, "n" + i);
        }
        long end = System.currentTimeMillis();
        System.out.println("Simple@Sharing SET: " + ((end - start)/1000.0) + " seconds");
    
        sharding.disconnect();
    }

这个是分布式直接连接，并且是同步调用，每步执行都返回执行结果。类似地，还有异步管道调用。

### 六、分布式直连异步调用 ###

@Test
    public void test6shardpipelined() {
        List<JedisShardInfo> shards = Arrays.asList(
                new JedisShardInfo("localhost",6379),
                new JedisShardInfo("localhost",6380));
    
        ShardedJedis sharding = new ShardedJedis(shards);
    
        ShardedJedisPipeline pipeline = sharding.pipelined();
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            pipeline.set("sp" + i, "p" + i);
        }
        List<Object> results = pipeline.syncAndReturnAll();
        long end = System.currentTimeMillis();
        System.out.println("Pipelined@Sharing SET: " + ((end - start)/1000.0) + " seconds");
    
        sharding.disconnect();
    }

### 七、分布式连接池同步调用 ###

如果，你的分布式调用代码是运行在线程中，那么上面两个直连调用方式就不合适了，因为直连方式是非线程安全的，这个时候，你就必须选择连接池调用。

@Test
    public void test7shardSimplePool() {
        List<JedisShardInfo> shards = Arrays.asList(
                new JedisShardInfo("localhost",6379),
                new JedisShardInfo("localhost",6380));
    
        ShardedJedisPool pool = new ShardedJedisPool(new JedisPoolConfig(), shards);
    
        ShardedJedis one = pool.getResource();
    
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            String result = one.set("spn" + i, "n" + i);
        }
        long end = System.currentTimeMillis();
        pool.returnResource(one);
        System.out.println("Simple@Pool SET: " + ((end - start)/1000.0) + " seconds");
    
        pool.destroy();
    }

上面是同步方式，当然还有异步方式。

### 八、分布式连接池异步调用 ###

@Test
    public void test8shardPipelinedPool() {
        List<JedisShardInfo> shards = Arrays.asList(
                new JedisShardInfo("localhost",6379),
                new JedisShardInfo("localhost",6380));
    
        ShardedJedisPool pool = new ShardedJedisPool(new JedisPoolConfig(), shards);
    
        ShardedJedis one = pool.getResource();
    
        ShardedJedisPipeline pipeline = one.pipelined();
    
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            pipeline.set("sppn" + i, "n" + i);
        }
        List<Object> results = pipeline.syncAndReturnAll();
        long end = System.currentTimeMillis();
        pool.returnResource(one);
        System.out.println("Pipelined@Pool SET: " + ((end - start)/1000.0) + " seconds");
        pool.destroy();
    }

### 九、需要注意的地方 ###

1.  事务和管道都是异步模式。在事务和管道中不能同步查询结果。比如下面两个调用，都是不允许的：
    
        Transaction tx = jedis.multi();
         for (int i = 0; i < 100000; i++) {
             tx.set("t" + i, "t" + i);
         }
         System.out.println(tx.get("t1000").get());  //不允许
        
         List<Object> results = tx.exec();
        
         …
         …
        
         Pipeline pipeline = jedis.pipelined();
         long start = System.currentTimeMillis();
         for (int i = 0; i < 100000; i++) {
             pipeline.set("p" + i, "p" + i);
         }
         System.out.println(pipeline.get("p1000").get()); //不允许
        
         List<Object> results = pipeline.syncAndReturnAll();
2.  事务和管道都是异步的，个人感觉，在管道中再进行事务调用，没有必要，不如直接进行事务模式。
3.  分布式中，连接池的性能比直连的性能略好(见后续测试部分)。
4.  分布式调用中不支持事务。
    
    因为事务是在服务器端实现，而在分布式中，每批次的调用对象都可能访问不同的机器，所以，没法进行事务。

### 十、测试 ###

运行上面的代码，进行测试，其结果如下：

Simple SET: 5.227 seconds
    
    Transaction SET: 0.5 seconds
    Pipelined SET: 0.353 seconds
    Pipelined transaction: 0.509 seconds
    
    Simple@Sharing SET: 5.289 seconds
    Pipelined@Sharing SET: 0.348 seconds
    
    Simple@Pool SET: 5.039 seconds
    Pipelined@Pool SET: 0.401 seconds

另外，经测试分布式中用到的机器越多，调用会越慢。上面是2片，下面是5片：

Simple@Sharing SET: 5.494 seconds
    Pipelined@Sharing SET: 0.51 seconds
    Simple@Pool SET: 5.223 seconds
    Pipelined@Pool SET: 0.518 seconds

下面是10片：

Simple@Sharing SET: 5.9 seconds
    Pipelined@Sharing SET: 0.794 seconds
    Simple@Pool SET: 5.624 seconds
    Pipelined@Pool SET: 0.762 seconds

下面是100片：

Simple@Sharing SET: 14.055 seconds
    Pipelined@Sharing SET: 8.185 seconds
    Simple@Pool SET: 13.29 seconds
    Pipelined@Pool SET: 7.767 seconds

分布式中，连接池方式调用不但线程安全外，根据上面的测试数据，也可以看出连接池比直连的效率更好。

### 十一、完整的测试代码 ###

package com.example.nosqlclient;
    
    import java.util.Arrays;
    import java.util.List;
    
    import org.junit.AfterClass;
    import org.junit.BeforeClass;
    import org.junit.Test;
    
    import redis.clients.jedis.Jedis;
    import redis.clients.jedis.JedisPoolConfig;
    import redis.clients.jedis.JedisShardInfo;
    import redis.clients.jedis.Pipeline;
    import redis.clients.jedis.ShardedJedis;
    import redis.clients.jedis.ShardedJedisPipeline;
    import redis.clients.jedis.ShardedJedisPool;
    import redis.clients.jedis.Transaction;
    
    import org.junit.FixMethodOrder;
    import org.junit.runners.MethodSorters;
    
    @FixMethodOrder(MethodSorters.NAME_ASCENDING)
    public class TestJedis {
    
        private static Jedis jedis;
        private static ShardedJedis sharding;
        private static ShardedJedisPool pool;
    
        @BeforeClass
        public static void setUpBeforeClass() throws Exception {
            List<JedisShardInfo> shards = Arrays.asList(
                    new JedisShardInfo("localhost",6379),
                    new JedisShardInfo("localhost",6379)); //使用相同的ip:port,仅作测试
    
    
            jedis = new Jedis("localhost"); 
            sharding = new ShardedJedis(shards);
    
            pool = new ShardedJedisPool(new JedisPoolConfig(), shards);
        }
    
        @AfterClass
        public static void tearDownAfterClass() throws Exception {
            jedis.disconnect();
            sharding.disconnect();
            pool.destroy();
        }
    
        @Test
        public void test1Normal() {
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) {
                String result = jedis.set("n" + i, "n" + i);
            }
            long end = System.currentTimeMillis();
            System.out.println("Simple SET: " + ((end - start)/1000.0) + " seconds");
        }
    
        @Test
        public void test2Trans() {
            long start = System.currentTimeMillis();
            Transaction tx = jedis.multi();
            for (int i = 0; i < 100000; i++) {
                tx.set("t" + i, "t" + i);
            }
            //System.out.println(tx.get("t1000").get());
    
            List<Object> results = tx.exec();
            long end = System.currentTimeMillis();
            System.out.println("Transaction SET: " + ((end - start)/1000.0) + " seconds");
        }
    
        @Test
        public void test3Pipelined() {
            Pipeline pipeline = jedis.pipelined();
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) {
                pipeline.set("p" + i, "p" + i);
            }
            //System.out.println(pipeline.get("p1000").get());
            List<Object> results = pipeline.syncAndReturnAll();
            long end = System.currentTimeMillis();
            System.out.println("Pipelined SET: " + ((end - start)/1000.0) + " seconds");
        }
    
        @Test
        public void test4combPipelineTrans() {
            long start = System.currentTimeMillis();
            Pipeline pipeline = jedis.pipelined();
            pipeline.multi();
            for (int i = 0; i < 100000; i++) {
                pipeline.set("" + i, "" + i);
            }
            pipeline.exec();
            List<Object> results = pipeline.syncAndReturnAll();
            long end = System.currentTimeMillis();
            System.out.println("Pipelined transaction: " + ((end - start)/1000.0) + " seconds");
        }
    
        @Test
        public void test5shardNormal() {
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) {
                String result = sharding.set("sn" + i, "n" + i);
            }
            long end = System.currentTimeMillis();
            System.out.println("Simple@Sharing SET: " + ((end - start)/1000.0) + " seconds");
        }
    
        @Test
        public void test6shardpipelined() {
            ShardedJedisPipeline pipeline = sharding.pipelined();
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) {
                pipeline.set("sp" + i, "p" + i);
            }
            List<Object> results = pipeline.syncAndReturnAll();
            long end = System.currentTimeMillis();
            System.out.println("Pipelined@Sharing SET: " + ((end - start)/1000.0) + " seconds");
        }
    
        @Test
        public void test7shardSimplePool() {
            ShardedJedis one = pool.getResource();
    
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) {
                String result = one.set("spn" + i, "n" + i);
            }
            long end = System.currentTimeMillis();
            pool.returnResource(one);
            System.out.println("Simple@Pool SET: " + ((end - start)/1000.0) + " seconds");
        }
    
        @Test
        public void test8shardPipelinedPool() {
            ShardedJedis one = pool.getResource();
    
            ShardedJedisPipeline pipeline = one.pipelined();
    
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) {
                pipeline.set("sppn" + i, "n" + i);
            }
            List<Object> results = pipeline.syncAndReturnAll();
            long end = System.currentTimeMillis();
            pool.returnResource(one);
            System.out.println("Pipelined@Pool SET: " + ((end - start)/1000.0) + " seconds");
        }
    }