r - Remove zombie processes using parallel package

Question

After I have played around for some time using R's parallel package on my Debian-based machine I still can't find a way to remove all zombie child-processes after a computation.

I'm searching for a general and OS independent solution.

Below a simple script illustrating the problem for 2 cores:

library(parallel)
testfun <- function(){TRUE}

cltype <- ifelse(.Platform$OS.type != "windows", "FORK", "PSOCK")
cl <- makeCluster(2, type = cltype)
p <- clusterCall(cl, testfun)
stopCluster(cl)

Unfortunately, this script leaves two zombie processes in the process table which only get killed if R is shut down.

Answer 1

This only seems to be an issue with "FORK" clusters. If you make a "PSOCK" cluster instead, the processes will die when you call stopCluster(cl).

Is there anything preventing you from using a "PSOCK" cluster on your Debian-based machine?