Java連接Redis數據庫 事務、管道和分佈式的調用方式

redis是一個著名的key-value存儲系統,而作爲其官方推薦的java版客戶端jedis也非常強大和穩定,支持事務、管道及有jedis自身實現的分佈式。

在這裏對jedis關於事務、管道和分佈式的調用方式做一個簡單的介紹和對比:

一、普通同步方式

最簡單和基礎的調用方式,

@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();
}

很簡單吧,每次set之後都可以返回結果,標記是否成功。

二、事務方式(Transactions)

redis的事務很簡單,他主要目的是保障,一個client發起的事務中的命令可以連續的執行,而中間不會插入其他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();
}

我們調用jedis.watch(…)方法來監控key,如果調用後key值發生變化,則整個事務會執行失敗。另外,事務中某個操作失敗,並不會回滾其他操作。這一點需要注意。還有,我們可以使用discard()方法來取消事務。

三、管道(Pipelining)

有時,我們需要採用異步方式,一次發送多個指令,不同步等待其返回結果。這樣可以取得非常好的執行效率。這就是管道,調用方法如下:

@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、管道中調用事務

就Jedis提供的方法而言,是可以做到在管道中使用事務,其代碼如下:

@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

經測試(見本文後續部分),發現其效率和單獨使用事務差不多,甚至還略微差點。

五、分佈式直連同步調用

@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();
}

這個是分佈式直接連接,並且是同步調用,每步執行都返回執行結果。類似地,還有異步管道調用。

六、分佈式直連異步調用

@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、分佈式連接池同步調用

如果,你的分佈式調用代碼是運行在線程中,那麼上面兩個直連調用方式就不合適了,因爲直連方式是非線程安全的,這個時候,你就必須選擇連接池調用。

@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,當然還有異步方式。

八、分佈式連接池異步調用

@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

事務和管道都是異步模式。在事務和管道中不能同步查詢結果。比如下面兩個調用,都是不允許的:

 Transaction tx = jedis.multi();
 for (int i = 0; i < 100000; i++) {
     tx.set("t" + i, "t" + i);
 }
 System.out.println(tx.get("t1000").get());  //不允許

 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()); //不允許

 List<Object> results = pipeline.syncAndReturnAll();

事務和管道都是異步的,個人感覺,在管道中再進行事務調用,沒有必要,不如直接進行事務模式。
分佈式中,連接池的性能比直連的性能略好(見後續測試部分)。

分佈式調用中不支持事務。

因爲事務是在服務器端實現,而在分佈式中,每批次的調用對象都可能訪問不同的機器,所以,沒法進行事務。

十、測試

運行上面的代碼,進行測試,其結果如下:

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,經測試分佈式中用到的機器越多,調用會越慢。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

分佈式中,連接池方式調用不但線程安全外,根據上面的測試數據,也可以看出連接池比直連的效率更好。

十一、完整的測試代碼

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,僅作測試


        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");
    }
}
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