Feature: track memory usage

[PyXiion]

While running benchmarks, I encountered an unexpected and massive spike in memory consumption. Some libraries hit nearly 28 GiB of RAM, bringing my system almost to death. Luckily, I managed to kill the process just in time.

I think memory usage tracking will be very useful.

Additionally, it would be helpful to add a warning in the README to alert users about potential high memory usage.

[tzcnt]

You're right, IIRC the peak with the current config for HPX is 29GB so I can barely complete the run on my 32GB Linux systems. libcoro peaks lower, at 14GB.

However, for the very fast libraries we are approaching the point where any system modifications will impact the performance noticeably, so I'm reluctant to add systematic memory tracking to every run.

I'll do a one-off tracking of the memory usages just for info to add to the README, and note how to skip the high usage / slow libraries (just drop concurrencpp, libcoro, HPX from the array on line 17 of the script)

[PyXiion]

Maybe we could just use getrusage at the very end of the process? It shouldn't affect the performance, but still gives us the MaxRSS

[tzcnt]

Want to open a PR? ;)

[PyXiion]

Yep.

To avoid copy pasting, I'll maybe write a little shared header