[R] Testing memory limits in R??

[Duncan Murdoch]

On 7/6/2009 3:52 PM, 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..

Individual vectors are limited to 2^31-1 elements, and the elements are 
8 bytes each in a double precision vector.  So executing

a <- numeric(2^30)

will use up 8 GB of memory.  You can try this with other variable names, 
and see how often it succeeds:

b <- numeric(2^30) # total now 16 GB
c <- numeric(2^30) # total now 24 GB, etc.

Duncan Murdoch