process_collector: fill in most statistics on macOS by mharbison72 · Pull Request #1600 · prometheus/client_golang (original) (raw)
Unfortunately, the virtual memory, resident memory, and network stats will require access to undocumented C functions. I was warned off of cgo in IRC because it would then have to be enabled in a bunch of different projects that use this module, but I already was against it because that would break the ability to cross-compile. There is no interface to dlopen built into golang. The github.com/ebitengine/purego module looks promising (I can cross-compile and call these methods), but I'm currently getting unexpected results. I'll follow up with that separately if I can get it working, but hopefully this stuff is pretty uncontroversial.
Tested on macOS 10.14.6 (amd64), macOS 14.6.1 (amd64), and macOS 15.0 (arm64) by spawning /usr/bin/ulimit -a -S and /usr/sbin/lsof -c $my_process from the test exporter process, and ps -o lstart,vsize,rss,utime,stime,command from the shell, and comparing results with the exported metrics.
I can't find documentation for RLIMIT_AS on macOS (specifically if it's in bytes or pages). It's currently being reported back as RLIM_INFINITY, which seems reasonable, because I've come across reports that the value is ignored anyway[1]. The bash 3.2 code for the built-in ulimit divides the value reported by getrusage(2) by 1024 when printing, as it does for RLIMIT_DATA, which is documented as being bytes in getrusage(2). The help for ulimit indicates it prints both in kbytes, so it's reasonable to assume this is already in bytes.