Could not get a resource from the pool AND Read timed out

[suresh inakollu]

Hi,

we are randomly getting below exceptions please suggest how to debug/fix

redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool at redis.clients.util.Pool.getResource(Pool.java:42) ~[jedis-2.4.2.jar:na] at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:90) ~[spring-data-redis-1.3.1.RELEASE.jar:1.3.1.RELEASE]

AND


Caused by: redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketTimeoutException: Read timed out at redis.clients.jedis.Protocol.process(Protocol.java:135) at redis.clients.jedis.Protocol.read(Protocol.java:191) at redis.clients.jedis.Connection.getIntegerReply(Connection.java:201) at redis.clients.jedis.BinaryJedis.exists(BinaryJedis.java:144) at org.springframework.data.redis.connection.jedis.JedisConnection.exists(JedisConnection.java:735)

AND my code is

JedisConnectionFactory factory = new JedisConnectionFactory();
JedisPoolConfig poolConfig = new JedisPoolConfig();
poolConfig.setMaxTotal(128);
factory.setPoolConfig(poolConfig);
factory.setUsePool(true);

[Salvatore Sanfilippo]

I'm a Java illiterate, but looks like the server is busy. Probably a
good start is https://redis.io/topics/latency

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--
Salvatore 'antirez' Sanfilippo
open source developer - Redis Labs https://redislabs.com

"If a system is to have conceptual integrity, someone must control the
concepts."
— Fred Brooks, "The Mythical Man-Month", 1975.

[hva...@gmail.com]

1. The first error message is coming from your Java client's class/module that's managing the pool of connections to external services (like Redis).  The pool manager is saying your client code asked for a new connection to be opened (to Redis), but the pool manager has reached the maximum number of open connections, so the new connection cannot be created.  The maximum number of connections is a configuration parameter to the pool manager, so it's under your control.

Now your task is to find out how many connections your code is opening to external services and understand why the pool manager was told to limit connections to a certain number, but the client code wants to open more than that number.  There could be a pool reserved for just the Redis connections, but there could also be a pool for all connections, not just the Redis ones.  Depends on the pool manager and the configuration.

2. The second error message says it was waiting for a reply from a connection to Redis, but it timed out before it received the reply.  There's no indication in this logfile of how long it waited.  Perhaps it waited a reasonable amount of time like 100 ms, but perhaps it waited an unreasonable amount of time, like 100 microseconds.

Investigate the read timeout configured into your Jedis client and see if it's reasonable.  If you think it is, have a look at the Redis slow log for the timestamp when Jedis complained about the timeout, and see if Redis was executing a slow command.  Check the other logs to see if Redis was up or down, or the Redis server was making Redis slow (e.g. because of swapping).  Check other apps to find out if there was a network issue that made communications between the client machine and the Redis machine slow or blocked.