Remove zombie processes using parallel package

r parallel-processing zombie-process
user625626 picture user625626 · Feb 28, 2012 · Viewed 7.4k times · Source

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

Joshua Ulrich picture Joshua Ulrich · Mar 1, 2012

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?

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