Show HN: Memstop – A tool to prevent OOM errors in parallel builds

I built a small tool to solve a problem on my build VM, which has 32 CPU cores but only 16GB of RAM. Running make -j32 would frequently fail when the OOM killer terminated a compiler process.

Throttling with a lower -j count felt inefficient, and make's load-average flag (-l) tracks CPU, not memory pressure.

So, I created Memstop. It's a simple LD_PRELOAD library that acts as a gatekeeper. Before each new process starts, it checks the available memory in /proc/meminfo. If memory is below a configurable percentage (default 10%), it simply pauses and waits for other processes to finish.

This allows my builds to use full parallelism, self-regulating by pausing when memory gets tight instead of crashing.

Usage is simple:

LD_PRELOAD=/path/to/memstop.so make -j32

You can control the threshold with the MEMSTOP_PERCENT environment variable.

The project is on GitHub (GPLv3), and I'm sharing it in case it's useful to others. I'd love to hear your thoughts!

Link: https://github.com/surban/memstop