[R] Is R on Windows multi-threaded

Duncan Murdoch murdoch at stats.uwo.ca
Fri Jan 11 15:58:39 CET 2008

On 1/11/2008 9:28 AM, Rees, David wrote:
> Hi,
> A previous thread suggests that R on Windows is multi-threaded
> http://tolstoy.newcastle.edu.au/R/help/03b/6946.html

Rgui is normally single threaded.  Rterm runs two threads in order to 
keep graphics windows updated.  Most computation happens in just one thread.
> When I'm running R 2.5.1 on a dual core pc I get Rgui.exe uses up to 50%
> of the available cpu and the rest is not used. i.e. it only uses one
> cpu. I'm soon going to get a nice shiny new 8 cpu machine which it would
> be very nice to fully utilize.
> Is there any way to get R to use all the cpus - should this happen
> automatically?

Not currently, other than by running multiple instances of R.  There are 
packages available to help multiple instances communicate.

There's also an experimental package by Luke Tierney in the works that 
parallelizes computations in one instance.  See this message:


Note his warning:

"It is not too hard to get parallel versions to use all available 
processor cores. The challenge is to make sure that the parallel 
versions don't run slower than the serial versions."

Duncan Murdoch

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