[R] Running two R instances at the same time

[Mario Valle]

Why instead you don't explore packages 'multicore' or 'snow+showfall 
(using sockets)'?
Ciao!
                mario

Peter Juhasz wrote:
> Dear R experts,
>
> please excuse me for writing to the mailing list without subscribing.
> I have a somewhat urgent problem that relates to R.
>
> I have to process large amounts of data with R - I'm in an
> international collaboration and the data processing protocol is fixed,
> that is a specific set of R commands has to be used.
>
> I wrote a perl program that manages creation of data subsets from my
> database and feeds these subsets to an R process via pipes.
>
> This worked all right, however, I wanted to speed things up by
> exploiting the fact that I have a dual-core machine. So I rewrote my
> perl driver program to use two threads, each starting its own R
> instance, getting data off a queue and feeding it to its R process.
>
> This also worked, except that I noticed something very peculiar: the
> processing time was almost exactly the same for both cases. I did some
> tests to look at this, and it seems that R needs twice the time to do
> the exact same thing if there are two instances of it running.
>
> I don't understand how is this possible. Maybe there is an issue of
> thread-safety with the R backend, meaning that the two R *interpreter*
> instances are talking to the same backend that's capable of processing
> only one thing at a time?
>
> Technical details: OS was Ubuntu 9.04 running on a Core2Dou E7300, and
> the R version used was the default one from the Ubuntu repository.
>
> Please see http://www.perlmonks.org/?node_id=792460 for an extended
> discussion of the problem, and especially
> http://www.perlmonks.org/?node_id=793506 for excerpts of output and
> actual code.
>
> Thanks for your answers in advance:
> Péter Juhász
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>   


-- 
Ing. Mario Valle
Data Analysis and Visualization Group            | http://www.cscs.ch/~mvalle
Swiss National Supercomputing Centre (CSCS)      | Tel:  +41 (91) 610.82.60
v. Cantonale Galleria 2, 6928 Manno, Switzerland | Fax:  +41 (91) 610.82.82