[R-pkg-devel] callr and CRAN policy on the max number of cores

[Henrik Bengtsson]

Two parallel processes are okay, so you can use two callr background
processes ("children"), as long as you don't do heavy computations on
the main R process ("parent"). This is commonly done in many R
packages, e.g.

library(parallel)
cl <- makeCluster(2)
y <- parLapply(cl = cl, X = 1:10, fun = slow_fcn)
stopCluster(cl)

/Henrik

On Wed, May 22, 2024 at 7:50 PM Shu Fai Cheung <shufai.cheung using gmail.com> wrote:
>
> Hil,
>
> I am exploring the use of callr in a package. I know that for packages
> that do parallel computing, we should not use more than two cores in
> examples, tests, etc. when being checked on CRAN.
>
> I believe I can use callr in tests and examples. How should I use
> callr in compliance with CRAN policy? Because even just one call to
> callr will start a new R session, should I limit the use of callr such
> that at any one time, only one background R session created by callr
> is active?
>
> Regards,
> Shu Fai
>
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