Allow providing custom ClusterTopologyRefresh implementation.

Feature Request

Is your feature request related to a problem? Please describe

During our load tests we have noticed an increasing level of CPU in each node of our Redis cluster that was proportional to the number of server connected.

Each server was on idle (no requests) and had a single Redis lettuce client instance running.

By looking at the Redis metrics we noticed that each node was constantly accepting new connections and reading the command logs we narrowed down the cause to the cluster topology refresh requests.

The DefaultClusterTopologyRefresh class creates new connection every time is called.

We have already increased the cluster topology refresh and we have switched the dynamicRefreshSources off, so the client refresh the topology is done against the seeds, in our case a single node.

With this adjustments we saw improvements but the CPU problem is still there.

This limits our ability to scale the number of server instances.

Describe the solution you’d like

Modify the DefaultClusterTopologyRefresh class to keep the connection alive so they can be re-used between topology refresh calls.

Maybe the ConnectionTracker class can be leveraged to store the connections between the calls.

Teachability, Documentation, Adoption, Migration Strategy

I will be happy to implement this feature, but I would like to know your opinion and maybe suggestions around the implementation.

Thanks

[mp911de]

That’s in place now.

[alessandrosimi-sa]

Nice, thanks a lot!