3. JedisPool

• To get a Jedis instance, you need to get it from JedisPool
• Jedis instances need to be returned to JedisPool
• If Jedis is used incorrectly, it also needs to be returned to JedisPool
• See code for examples

1) JedisPoolUtil

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;
 
public class JedisPoolUtil {
  
 private static volatile JedisPool jedisPool = null;// Volatile variables are not cached by the local thread, and reads and writes to them are direct operations on shared memory.
  
  private JedisPoolUtil(a) {}
  
  public static JedisPool getJedisPoolInstance(a)
 {
     if(null == jedisPool)
    {
       synchronized (JedisPoolUtil.class)
      {
          if(null == jedisPool)
         {
           JedisPoolConfig poolConfig = new JedisPoolConfig();
           poolConfig.setMaxActive(1000);
           poolConfig.setMaxIdle(32);
           poolConfig.setMaxWait(100*1000);
           poolConfig.setTestOnBorrow(true);
            
            jedisPool = new JedisPool(poolConfig,"127.0.0.1"); }}}return jedisPool;
 }
  
  public static void release(JedisPool jedisPool,Jedis jedis)
 {
     if(null! = jedis) { jedisPool.returnResourceObject(jedis); }}}Copy the code

(2) call

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
 
public class Test01 {
  public static void main(String[] args) {
     JedisPool jedisPool = JedisPoolUtil.getJedisPoolInstance();
     Jedis jedis = null;
     
     try 
     {
       jedis = jedisPool.getResource();
       jedis.set("k18"."v183");
       
     } catch (Exception e) {
       e.printStackTrace();
     }finally{ JedisPoolUtil.release(jedisPool, jedis); }}}Copy the code

Configuration summary

JedisPool configuration parameters are mostly assigned by the corresponding items of JedisPoolConfig.

MaxActive: Controls how many jedis instances can be allocated to a pool, using pool.getResource(); If the value is -1, there is no limit; If the pool has already allocated maxActive jedis instances, the pool is in the exhausted state. MaxIdle: Controls the number of jedis instances in a pool that are in idle state. Whenustedaction: Action to be taken when all jedis instances in the pool have been allocated. By default, there are three. When_hausted_fail –> NoSuchElementException is thrown when there is no jedis instance. When_hausted_block –> blocked, or JedisConnectionException thrown when maxWait is reached; When_hausted_grow –> indicates that a new jedis instance is created, i.e. maxActive is useless. MaxWait: Indicates the maximum wait time when borrow a Jedis instance. If the wait time is exceeded, JedisConnectionException is thrown directly. TestOnBorrow: Whether to check connection availability when obtaining a Jedis instance (ping()); If true, the resulting Jedis instances are all available;

TestOnReturn: whether to check connection availability when a jedis instance is sent to the pool (ping());

TestWhileIdle: If true, an idle object evitor thread will scan the idle object. If validate fails, the object will be dropped from the pool. This item is only meaningful when timeBetweenEvictionRunsMillis is greater than 0;

TimeBetweenEvictionRunsMillis: it means the idle object evitor between two scans to sleep the number of milliseconds;

NumTestsPerEvictionRun: indicates the maximum number of objects scanned by the Idle Object evitor at a time.

MinEvictableIdleTimeMillis: an object at least stay in the idle state of the shortest time, and then you can be idle object evitor scans and expelling; This item is only meaningful when timeBetweenEvictionRunsMillis is greater than 0;

SoftMinEvictableIdleTimeMillis: on the basis of minEvictableIdleTimeMillis, joined at least minIdle target has had in the pool. If it is -1, Evicted does not expel any objects based on idle time. If minEvictableIdleTimeMillis > 0, then this setting meaningless, and is only meaningful when timeBetweenEvictionRunsMillis is greater than 0;

When lifo: borrowObject returns an object, DEFAULT_LIFO (last in first out, i.e. the most frequently used queue similar to cache) is adopted. If it is False, it indicates FIFO queue.

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = The default Settings of JedisPoolConfig for some parameters are as follows: testWhileIdle=true minEvictableIdleTimeMills=60000 timeBetweenEvictionRunsMillis=30000 numTestsPerEvictionRun=-1