[R] Testing memory limits in R??

[Peter Dalgaard]

Scott Zentz wrote:
> Hello Everyone,
> 
>    We have recently purchased a server which has 64GB of memory running 
> a 64bit OS and I have compiled R from source with the following config
> 
> ./configure --prefix=/usr/local/R-2.9.1 --enable-Rshlib 
> --enable-BLAS-shlib --enable-shared --with-readline --with-iconv 
> --with-x --with-tcktk --with-aqua --with-libpng --with-jpeglib
> 
> and I would like to verify that I can use 55GB-60GB of the 64GB of 
> memory within R. Does anyone know how this is possible? Will R be able 
> to access that amount of memory from a single process? I am not an R 
> user myself but I just wanted to test this before I turned the server 
> over to the researchers..

Hmm, it's slightly tricky because R often duplicates objects, so you may 
hit the limit only transiently. Also, R has an internal 2GB limit on 
single vectors. But something like this

Y <- replicate(30, rnorm(2^28-1))

should create an object of about 30*2GB. Then lapply(Y, mean) should 
generate 30 very good and very expensive approximations to 0.

(For obvious reasons, I haven't tested this on a 1GB ThinkPad X40....)


-- 
    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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