Hello,
I have a minimal example that shows a problem I'm having with parallel
processing.
library(parallel)
mcmapply(function(x, y)
{
print("Running")
Sys.sleep(10)
}, as.list(1:10), as.list(10:1), mc.cores = 16, SIMPLIFY = FALSE)
I see "Running" printed once every ten seconds. I read the documentation for
mcmapply, but I don't understand why it wouldn't print all ten output
statements almost at once, then wait for about ten seconds, then return to the
prompt. Is it documented in another location ?
My problem is that I have a section of code that takes a long time, which I
have replaced with Sys.sleep in the above example, but when I look at the
output of top, I only see 1 CPU being used. The computer has 16 processors.
> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-pc-linux-gnu (64-bit)
locale:
[1] LC_CTYPE=en_AU.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_AU.UTF-8 LC_COLLATE=en_AU.UTF-8
[5] LC_MONETARY=en_AU.UTF-8 LC_MESSAGES=en_AU.UTF-8
[7] LC_PAPER=en_AU.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_AU.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] parallel stats graphics grDevices utils datasets methods
[8] base
loaded via a namespace (and not attached):
[1] tools_3.1.0
--------------------------------------
Dario Strbenac
PhD Student
University of Sydney
Camperdown NSW 2050
Australia
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
