redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool

[SivaTharun2024]

I am seeing the below weird error, while using the jedis client to connect to the managed redis server instance, we have setup 10 different instances of the service, where we are using jedis client to connect to the redis instance.

The issue is that, over time we have been noticing that one or more service instances, is not able to connect to the redis server and we see the below error in the app logs.

Connect error to redis server:10.xxx.xxx.x;Exception:redis.clients.jedis.exceptions.JedisException: Could not get a resource from the pool

Only after restarting the effected app instance, the issue is getting resolved. i have checked the client info on the redis server, i have noticed that there are no issue on the available connections, nor there are any blocked clients.

Attaching the configuration code , on how we are setting up the jedis client for reference.

private static final RedisClient INSTANCE = new RedisClient();

 static {
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(RedisClient.MAX_CONNECTIONS);
        config.setMaxIdle(RedisClient.MAX_IDLE_CONNECTIONS);
        config.setMaxWaitMillis(MAX_WAITINMILLIS);
        INSTANCE.init(config);
    }


  void init(JedisPoolConfig config) {
        setPoolConfig(config);
        setRedisHost(resolveRedisHost(RedisClient.DEFAULT_REDIS_HOST));
        initJedisPool(poolConfig, redisHost);
    }


 private void setPoolConfig(JedisPoolConfig jedisPoolConfig) {
        this.poolConfig = jedisPoolConfig;
    }

   private void setRedisHost(String redisHost) {
        this.redisHost = redisHost;
    }

 private void initJedisPool(JedisPoolConfig poolConfig, String redisHost) {
        this.connectionPool = new JedisPool(poolConfig, redisHost, Protocol.DEFAULT_PORT, RedisClient.TIMEOUT_MS);
    }

 
public Jedis getJedisClient() {
        try {
            return connectionPool.getResource();
        } catch (Exception e) {
            logRedisFailure(e);
            return null;
        }
    }

[sazzad16]

Firstly, please provide whole stacktrace.

[SivaTharun2024]

This is the stacktrace for your reference.

at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
at org.apache.commons.pool2.impl.LinkedBlockingDeque.pollFirst(LinkedBlockingDeque.java:942)
       local variable: org.apache.commons.pool2.impl.LinkedBlockingDeque#1
  at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:317)
       local variable: org.apache.commons.pool2.impl.GenericObjectPool#1
       local variable: java.time.Duration#36
  at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:428)
  at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:232)
  at redis.clients.util.Pool.getResource(Pool.java:49)
  at redis.clients.jedis.JedisPool.getResource(JedisPool.java:226)
       local variable: redis.clients.jedis.JedisPool#1
  at com.test.qi.rest.util.RedisClient.getJedisClient(RedisClient.java:118)
       local variable: com.test.qi.rest.util.RedisClient#1
  at com.test.qi.rest.util.RedisClient.getCount(RedisClient.java:199)

[sazzad16]

It can be seen that a resource (Jedis object) could not be received from the Pool. It is possible that all of MAX_CONNECTIONS resources in the Pool were busy and not enough resources were freed within MAX_WAITINMILLIS to serve the operation.

[sazzad16]

Secondly, are you making sure if the Jedis object received from getJedisClient() is closed?

[SivaTharun2024]

Yes, we have defined fetch, setKeyWithTTL and count methods, to retrieve the relevant details for the corresponding keys, as below. Here we are making sure, that our client is closed whenever data insertion/retrieval operations are being performed.

public String fetch(String key) {
      
        String value = null;
        Jedis client = getJedisClient();
        if (client != null) {
            try {
                value = client.get(key);
                String data = "value=" + value;
            } catch (Exception e) {
                String data = "Failure=" + e.getMessage();
      			logFailure(e,data);
            } finally {
                client.close();
            }
        }
        return value;
    }