Using R in parallel on a 2 processor machine

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How about installing an operating system that knows its way around that much
RAM?
-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch]On Behalf Of Graham Law
Sent: Monday, November 15, 2004 9:12 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Using R in parallel on a 2 processor machine

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.

Graham

Graham Law

Senior Scientist

Epidemiology and Genetics Unit

Department of Health Sciences

University of York

York YO10 5DD UK

(t) +44 (0) 1904 32 1883

(m) +44 (0) 790 500 8828

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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

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