[R] R and memory

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Jan 10 18:30:01 CET 2001

On Wed, 10 Jan 2001, Meriema Belaidouni wrote:

> Hello
> I have some problems to read large data file with R.

We need to know more to be able to help with that.

> can someone tell me why running
> R --visze=30M --nsize=2000k
> uses in fact 63M?

Let me try.  That allocates (modulo a typo) 30Mb of heap and 2 million
cons cells.  I will assume you are using a 32-bit system and a version of
R prior to 1.2.0.  Then a cons cell is 20 bytes, and so the total space is
38.2Mb for those.  So (and I tried it) the workspace is 68.2Mb. However,
depending on your system, not all of that may appear under say top, and in
any case the R process needs another 4Mb or so for code.

The current version of R may well behave differently, and we do suggest
that you do not use those flags any more.

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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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