I run (k)Ubuntu 12.04.2 and R 3.0.1
I wrote a bunch of code that used to run in parallel, but now it no longer does. Not even this runs in parallel any more:
library(doMC)
registerDoMC(4)
Results = foreach (i = 1:1e6, .combine = "c") %dopar% {
sqrt(i)
}
And that definitely should. What I think broke it is either the R 3.0.1 update or a -dev, -devel
BLAS package I installed. (openBLAS I think)
I've tried system(sprintf("taskset -p 0xffffffff %d", Sys.getpid()))
as suggested elsewhere, and get this result:
pid 2415's current affinity mask: 1
pid 2415's new affinity mask: f
I've also tried running R with:
taskset 0xffff R
However after either of these steps running the loop still only uses one core.
I want parallel processing back! How can I get it?
I found the solution! Ironically, to get parallel processing back I had to do both of the steps I mentioned in the Q at the same time
So, start R with
Then run
Within R.
Voila, parallel processing returns