Docker image switched to use jemalloc

[stefansundin]

I have pushed new docker images where I changed the base image to one that built Ruby with jemalloc. In theory this should give some memory usage benefits. I figured I'll open this discussion as a place where people can report their experience.

Please feel free to post images of what your memory usage looks like, and if there's any benefits or disadvantages to the jemalloc change.

I'm using my own Ruby base image which I have maintained for years. I've been meaning to switch (or at least try out) the jemalloc option ever since I learned about it many years ago, but I just never got around to it.

Since switching to Fly, the public version is more memory constrained that it has ever been. On Heroku I had 512 MB but the free Fly option only gives you 256 MB. 🤐

So lets try jemalloc now, maybe it will make a difference. Will use this thread to keep track of how it goes. I actually already deployed this change to Fly yesterday and here's the difference so far:

• Blue = Ruby v3.2.0 on bullseye
• Orange = Ruby v3.2.0 on bookworm
• Yellow = Ruby v3.2.0-jemalloc on bookworm

I switched to bookworm so that I can more easily enable yjit later. No idea if this will have a detrimental effect on memory, in which case I will probably revert it.

Anyway.. long term I think I have to rewrite RSS Box into another language if I want to keep it possible to run with very low memory. No concrete plans on this yet though.