[R] Using R in parallel on a 2 processor machine

Prof Brian Ripley ripley at stats.ox.ac.uk
Mon Nov 15 15:49:26 CET 2004

Try reading the rw-FAQ!

There is no way user processes in Windows XP can access all 4Gb of the 
address space, but if you tune both R and XP correctly you should be able 
to get above 2Gb in total.  See the rw-FAQ for how to tune R.

Nevertheless, as you have already been told, it is a lot easier to do this
under a

On Mon, 15 Nov 2004, Graham Law wrote:

> Hi,
> I have installed R (2.0.0) onto a two processor machine running Windows
> XP (these two processors have been split into 4 logical processors),
> with 4Gb of RAM.  Rather than multi-threading, I wanted to run 2
> instances of R on the machine in parallel, which uses two of the logical
> processors.  Unfortunately, R seems to be accessing a total of 1Gb of
> RAM, not taking advantage of 2 lots of 1Gb.  This has led to memory
> problems, with one R process using the RAM, and the other one running
> into memory problems.

> Looking at previous posts on this issue, I have tried using gc(), to
> take back unused memory.  This has allowed the two parallel processes to
> work, but has not given me access to the other 3Gb.
> Any help would be much appreciated into how R may run in parallel using
> more than 1Gb.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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