Short answer: You don't want to override that limit in your R package. Don't do it.
Long answer: You'll find the reason for this in the 'CRAN Repository Policy' (https://cran.r-project.org/web/packages/policies.html). Specifically, the following passage: "Checking the package should take as little CPU time as possible, as the CRAN check farm is a very limited resource and there are thousands of packages. Long-running tests and vignette code can be made optional for checking, but do ensure that the checks that are left do exercise all the features of the package. **If running a package uses multiple threads/cores it must never use more than two simultaneously: the check farm is a shared resource and will typically be running many checks simultaneously.** Examples should run for no more than a few seconds each: they are intended to exemplify to the would-be user how to use the functions in the package." Basically, you can use two cores to demonstrate or validate (e.g. in package tests) that your code *can* run in parallel, but you must not use more than that to demonstrate that your code can "run super fast". Even-longer answer: See my blog post 'Please Avoid detectCores() in your R Packages' (https://www.jottr.org/2022/12/05/avoid-detectcores/) from 2022-12-05 for even more reasons. /Henrik On Sun, Jul 2, 2023 at 9:55 AM Ravi Varadhan via R-help <r-help@r-project.org> wrote: > > This is the specific error messsage from R CMD check --as-cran > > > Error in .check_ncores(length(names)) : 16 simultaneous processes spawned > Calls: prepost -> makeCluster -> makePSOCKcluster -> .check_ncores > Execution halted > > > Thanks, > Ravi > > ________________________________ > From: Ravi Varadhan > Sent: Saturday, July 1, 2023 1:15 PM > To: R-Help <r-help@r-project.org> > Subject: Number of Cores limited to two in CRAN > > Hi, > I am developing a package where I would like to utilize multiple cores for > parallel computing. However, I get an error message when I run R CMD check > --as-cran. > > I read that CRAN limits the number of cores to 2. Is this correct? Is there > any way to overcome this limitation? > > Thank you, > Ravi > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.