readOnlyForReplica flag question

[ruispereira]

Checking master branch, in the class https://github.com/redis/jedis/blob/master/src/main/java/redis/clients/jedis/DefaultJedisClientConfig.java there's a new flag to allow reading from replica nodes. This can be used with sentinels? Or in a master-slave configuration?

Another question is when a new release will be shipped with this feature?

[sazzad16]

It is meant for READONLY command which is dedicated for Redis Cluster.

Thank you for asking this. I guess we'd have to rename+document it further.

[ruispereira]

Thank you for your quick answer!
So, my team is using redis sentinels, for high availability, and using Spring Redis OM, we are reaching always master node for read and writes and we are getting 100% CPU most of the time for master node.
Is there any way to force reads to go to replica nodes instead of reaching always master node?
Thanks in advance.

[sazzad16]

@ruispereira Not readily.

You may extend SentineledConnectionProvider and override getConnection(CommandArguments) method to achieve that.

[ruispereira]

Thank you!
And is there any way to known if the current operation is a read or write operation?

[sazzad16]

Using CommandArguments.getCommand() you would have recognize.
In your case it's enough to recognize only your HOT READ commands.

[ruispereira]

Ok, understand!
One more question, how can i get the replicas? I see that jedis class have a sentinelReplicas method to get the list of replicas, i need to use this right? Do i have to have a thread, like the sentinel have, to known if a given replica die or something, so we will always have the list of replicas fresh..

[sazzad16]

It's up to you.

Your suggestion is of course a solution.

Someone else may consider maintaining list on their own and/or communicating with the replicas by executing a command (i.e. ping).

In either of the ways, separate thread could be needed.