(Not) using detectCores() in packages

[achubaty]

Thank you for the great blog post (https://www.jottr.org/2022/12/05/avoid-detectcores/).

I'd like to add another reason to avoid detectCores() in packages: it's becoming more common to encounter machines/clusters with more cores than R has available socket connections (~125).

At least with availableCores() a user can override the default value to limit the maximum number of cores returned.

[HenrikBengtsson]

Excellent point. I've updated the blog post with a new Section 'Issue 3: detectCores() may return too many cores' covering this problem. Thank you so much.

[HenrikBengtsson]

BTW, your comment made me think if we can automate this even further in availableCores(). Maybe we can introduce something like

ncores <- availableCores(constraints = "connections")

I've created futureverse/parallelly#91 to track this idea.

UPDATE: This was implemented in parallelly 1.33.0 (2022-12-14).

[achubaty]

Yes! That would be really great. I'll add comments/questions at that issue tracker.