ConnectionMultiplexer opens multiple connections to Sentinel and Standalone

Hello,

Currently we are using StackExchange.Redis and custom connection pooling implementation that opens multiple connections to Redis as we have high volume of operations and usage in our applications which sometimes caused Timeouts. As of today we are using the following code:

multiplexer = ConnectionMultiplexer.Connect(redisConfiguration.ConfigurationOptions);

We recently updated our StackExchange.Redis version to the latest stable (v2.6.96) and I saw that there is a fix regarding the Endpoints collection which was getting modified on every other Connect method call after the first one. Another change we saw in one of the threads here in Github was that the CommandMap is now handled internally and does not need to be set when using Sentinel. I passed a logger to see what is happening and modified the code like this:

multiplexer = ConnectionMultiplexer.Connect(redisConfiguration.ConfigurationOptions, streamWriter);

What I saw from the logs surprised me. First there is a connection to Sentinel and then to Standalone. However if we use SentinelConnect only one connection to Sentinel gets opened:

multiplexer = ConnectionMultiplexer.SentinelConnect(redisConfiguration.ConfigurationOptions, streamWriter);

The reason we are updating to the latest version and to the usage of ConnectionMultiplexer.SentinelConnect is because when we open more connections we are getting the following error:

Sentinel: The ConnectionMultiplexer is not a Sentinel connection. Detected as: Standalone

In our case, we only need Sentinel connection as we do not need multiple Standalone connections being opened. Can you advise us on whether we should use Connect or SentinelConnect and why does Connect opens connections to Sentinel and Standalone?

Here are the logs when using ConnectionMultiplexer.Connect: https://pastebin.com/pLbdVgtH
Here are the logs when using ConnectionMultiplexer.SentinelConnect: https://pastebin.com/Y1Y1y5qy

Regards,
Martin

Start at the ConnectionMultiplexer.Connect and SentinelConnect entry points, then compare the two linked log captures to trace why Sentinel and Standalone connections are opened. Review the issue comments for the current understanding; done means documenting which method is intended for this configuration and whether the observed connection behavior is a bug.