[R] Memory usage decreases drastically after save workspace, quit, restart, load workspace
Prof Brian Ripley
ripley at stats.ox.ac.uk
Sat Aug 26 10:55:25 CEST 2006
On Sat, 26 Aug 2006, Klaus Thul wrote:
> Dear all,
> I have the following problem:
> - I have written a program in R which runs out of physical memory
> on my MacBook Pro with 1.5 GB RAM
How does R know about physical memory on a virtual-memory OS? I presume
the symptom is swapping by your OS, but how do you attribute that to R?
> - The memory usage is much higher then I would expect from the
> actual data in my global environment
> - When I save the workspace, quit R, restart R and load the
> workspace again, memory usage is much less then before
> (~50 MB instead of ~1.5 GB), although nothing seems to be missing.
> - It doesn't seem to be possible to reduce the amount of memory
> used by calling gc()
> - the behavior is independent of if I use R in command line or from
> GUI, so I can exclude a problem of the Mac GUI
> Any suggestions what the problem might be or how I could debug this?
How are you measuring memory usage?
If this is by gc(), note that lazyloading is one-way, and memory increases
after you use a lazyloaded object in a session. This can be dramatic
where datasets are involved.
If you are asking the OS about memory usage, return of memory to the OS is
a rather haphazard and OS-specific issue. On some OSes virtual memory is
not actually reclaimed from applications until it is needed (or ever).
It is certainly possible that something you are using has a memory leak,
but valgrind has been used to plug those on the most-used parts of R.
I at least need more precise indications of what you observed to be able
to comment 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 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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