[R] error with more 100 forked processes

[Ivan Krylov]

On Fri, 8 Apr 2022 22:02:25 +0200
Guido Kraemer via R-help <r-help using r-project.org> wrote:

>  > cl <- makeForkCluster(128)  
> Error in UseMethod("sendData") :
>    no applicable method for 'sendData' applied to an object of class
> "NULL"

In order to communicate with the workers, R creates connection objects.
Unfortunately, the memory for connection objects in R has a
statically-defined limit of 128. (A few connections are used by
default, and a few more will likely be used by user code during the
actual program run.)

Try increasing the limit in #define NCONNECTIONS in
src/main/connections.c and re-compiling R.

See also: https://github.com/HenrikBengtsson/Wishlist-for-R/issues/28
According to Henrik Bengtsson, R should work well even with as many
as 16381 possible connections, but then you may run into OS limits on
file descriptors.


-- 
Best regards,
Ivan