Default number of workers: Look at the affinity mask instead of the number of CPUs?

[vext01]

Hi,

I was looking for a thread pool, and found this repo. Thanks for working on this.

I was browsing the dependencies and saw that you use num_cpus to decide how many worker threads to use by default:

let num_threads = self.num_threads.unwrap_or_else(num_cpus::get);

Would it not be better to look into the affinity mask to get this default? The system may have 64 cores, but have the process pinned to, e.g. 4 cores. This would cause contention.

I found this crate, which might help (disclaimer, I've not used it and I'm not sure how portable it is):
https://crates.io/crates/core_affinity

Thanks

[frewsxcv]

from what i understand, num_cpus::get uses the affinity mask whereas num_cpus::get_physical returns the unpinned physical number of cores. i might be wrong though....

[dns2utf8]

Good idea.

If you are using a SGE managed cluster you can use my latest crate son of grid engine.
You can use get_pinned_threadpool() for a correctly pinned pool there.

I think the pinning should not be the default, but an option with the builder.