分享程序员开发的那些事...
更新时间：2022-09-11 23:10:57
1.pom.xml中依赖如下：
|
1
2
3
4
5
|
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.6.1</version>
</dependency>
|
2.jedis pool中ping的产生
线上storm的bolt使用jedis pool操作redis，高峰时压力一直比较大，每s处理量多达10w/s，redis持续跑满（单线程，cpu100%），对monitor数据分析，发现50%以上的都是ping操作，ping是用来检测redis是否可用的操作，在jedis pool中由两个参数控制：
|
1
2
|
setTestOnBorrow //获取连接时是否触发pingsetTestOnReturn //释放连接时是否触发ping |
默认两个值都是true的，设置为false即可
3.获取不到资源时jedis的处理
1）当setBlockWhenExhausted设置为true(默认即为true)时，阻塞setMaxWaitMillis时间（默认为-1,会一直阻塞），超过时间限制则抛出异常：
|
1
2
3
4
5
6
7
8
9
|
Exception in thread "main" redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool at redis.clients.util.Pool.getResource(Pool.java:53)
at redis.clients.jedis.JedisPool.getResource(JedisPool.java:99)
at main.java.JedisPoolTest.main(JedisPoolTest.java:20)
Caused by: java.util.NoSuchElementException: Timeout waiting for idle object at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:442)
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:360)
at redis.clients.util.Pool.getResource(Pool.java:51)
... 2 more
|
2)当setBlockWhenExhausted(false);设置为false时，直接抛出异常，不会阻塞
4.jedis的默认db都是0，可以通过构造函数的参数进行设置
5.防止资源泄露，在catch异常的时候使用JedisPool.returnBrokenResource释放连接，可以使用JedisPool.getNumActive获取当前的活动连接数
6.pool的初始化经常使用静态代码块完成
7.sharding的模式也是支持pipline的
附1个jedissharding pipeline的例子：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
|
package main.java;import redis.clients.jedis.JedisPoolConfig;import redis.clients.jedis.JedisShardInfo;import redis.clients.jedis.ShardedJedisPool;import redis.clients.jedis.ShardedJedis;import redis.clients.jedis.ShardedJedisPipeline;import java.util.List;import java.util.LinkedList;public class JedisPoolTest { private static ShardedJedisPool pool = null;
private static ShardedJedisPipeline pip = null;
public static void main(String[] args) {
JedisPoolConfig jc = new JedisPoolConfig();
jc.setBlockWhenExhausted(false);
jc.setMaxIdle(8);
jc.setMaxTotal(20);
jc.setTestOnBorrow(false);
jc.setTestOnReturn(false);
jc.setMaxWaitMillis(-1);
JedisShardInfo jedisShardInfo1 = new JedisShardInfo("192.168.101.42",6379);
JedisShardInfo jedisShardInfo2 = new JedisShardInfo("192.168.101.42",6380);
List<JedisShardInfo> list = new LinkedList<JedisShardInfo>();
list.add(jedisShardInfo1);
list.add(jedisShardInfo2);
pool = new ShardedJedisPool(jc, list);
ShardedJedis jedis = pool.getResource();
pip = jedis.pipelined();
long start = System.currentTimeMillis();
for(int i = 0;i <= 100;i++){
String key = "shardpool" + String.valueOf(i);
pip.del(key);
pip.set(key, "test");
}
pool.returnResource(jedis);
pip.syncAndReturnAll();
long end = System.currentTimeMillis();
long elapse = end - start;
System.out.println("10000 itmes elapse time is " + String.valueOf(elapse));
}
} |