mps VS mmtk-core

I have a library which has an extremely slow free, around 2m for large files, because of unnaturally scattered allocation patterns, but this old conservative GC didn't help at all. It was about 40% slower with libgc. mimalloc was a bit better. Best would be a properly fast GC, like mps https://github.com/Ravenbrook/mps, but this would be too much work.

The first thing you should look at is MPS (see https://github.com/Ravenbrook/mps and https://www.ravenbrook.com/project/mps/). It's open source, professionally maintained and very powerful, and it was used e.g. in Dylan and LispWorks.

I wonder how the MMTK compares to the venerable Ravenbrook MPS https://www.ravenbrook.com/project/mps/ which originated in Harlequin’s programming language implementations, particularly Dylan.

I am trying to implement garbage collection for my language because I want memory management for arrays/lists and strings. I am looking through LLVM's garbage collection page but the documentation isn't great. Are there any other resources that offer more concrete steps to implement garbage collection? Would it be wise to circumvent LLVM all together for garbage collection and only use something like the Memory Pool System? Thanks!

This post seems related to the authors of MPS (1) that seems to be a general garbage-collector to use with various languages.

Many GC'd languages really didn't bother with stack-allocating variable-size entities, and regardless of if they did then _precicely_ scanning the stack would be complicated without compiler help.

If the compiler doesn't leave any info to the GC, then it can't know if it's scanning a pointer or a float and if your GC strategy relies on compacting memory (ie moving objects) then trying to guess between a float or a pointer can become fatal.

(1) https://github.com/Ravenbrook/mps

Great learning project, I'm glad the author is having fun.

If they're interested in bolting on a GC, it couldn't hurt to look at MMtk. (https://www.mmtk.io/) Some high quality collection algorithms, written to be pluggable to various VMs, and written in Rust.

just here to mention https://github.com/mmtk/mmtk-core crate which provides garbage collectors. The only problem is requiring threads, which makes it unsuitable for wasm.

AFAIK, no. The opposite is true with MMtk (https://www.mmtk.io), which is a toolkit with many GC algorithms implemented that has been plugged into other runtimes, including, as it happens, OpenJDK.

IME the MPS is hard to set up correctly, and I've heard in Clasp they got in performance trouble, as per-thread allocation buffers were too small and they couldn't make the buffers larger. But indeed being conservative on the stack is a fine choice; someone mentioned Boehm being easy to use, and the MMTk is a newer option which allows for bump-allocation and being precise on the heap (like MPS), but at the moment you have to provide your own stack scanning code.