[R] R with multiple processors

Tony Long tdlong at uci.edu
Thu Feb 15 18:16:54 CET 2001

R is inefficient enough that if you need 12 processors you may 
consider writing your function in C.  Alternatively you can identify 
the part of your R code where most your CPU cycles are being used and 
make that a function in C.  Porting large chucks of R code or even 
small routines that are gobbling up CPU cycles can give your orders 
of magnitude speed changes!   Once you learn how to do it, letting R 
call external compiled function is really very easy.

At 8:26 AM -0800 2/15/01, Thomas Lumley wrote:
>On Wed, 14 Feb 2001, Isabel Canette wrote:
>>  Hello.
>>  The laboratory where I work has the possibility to get a Sun machine with 12
>>  processors. My question is: can R be used to implememt parallel algorithms
>>  which take into account the several processors? Is there a way to 
>>run *threads*
>>  in R?
>>  If this is possible, would somebody share his/her experiences?
>It is not possible to run threads in R.  However, it is possible to call
>other threaded code, as the R-Java and R-Tcl interfaces demonstrate.  You
>could probably call parallel C or Fortran code. Alternatively, for a
>problem with fairly low communication requirements you could control
>multiple R processes from one central program and feed them each  bits of
>I usually want to run any given computation lots of times, so the solution
>is easy: instead of running it 1000 times on 1 processor, run it 80 times
>on each of 12 processors.
>	-thomas
>Thomas Lumley			Asst. Professor, Biostatistics
>tlumley at u.washington.edu	University of Washington, Seattle
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Tony Long
Ecology and Evolutionary Biology
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University of California at Irvine
Irvine, CA

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