Redis memory footprint in a empty instance has increased up to 3MB in Redis 4, why?

[David Torres]

This is not really an issue, it's just there is this surprising change for me and I'd like to understand the internals!

What I understand by memory footprint in an empty instance

You install redis, start it, execute INFO command and annotate VmRSS size. 

The change

Redis 2 and Redis 3 used ~1MB for an empty instance. Redis 4 is using ~3MB. This is also shown in the FAQ https://redis.io/topics/faq (the section about memory footprint states 3MB for an empty instance, previous version of this FAQ did state 1MB).

Why I think it matters? 

Obviously passing from 1MB to 3MB is not a huge change, specially for server-related use cases. BUT, Redis is targetting now to IOT systems (Raspberry Pi is the first!). I expect STREAM datatype as the key feature to use Redis in any IOT development (home and production developments). Therefore, this small difference in a very tiny system could make Redis not usable at all in some specific environments.

Reasons for that increasement

Please, I need feedback on that! Some ideas: the new module system, clustering features....

Improvements (maybe)

If there is some features consuming this extra RSS memory, maybe could be an option to have configuration flags to enable or disable these features, allowing deployers to adapt Redis to constrained environments.

Thanks for your valuable comments!