[R] R not giving memory back to system?

Thomas Lumley tlumley at u.washington.edu
Mon Nov 26 23:51:16 CET 2001

On Mon, 26 Nov 2001, Gardar Johannesson wrote:

> This might be because I didn't get it right, but; I thought R would
> release memory back to the system as (big) objects get removed?

You can give it back, but you can't force the OS to take it. This is from
the comp.lang.c newsgroup's FAQ (http://www.eskimo.com/~scs/C-faq/top.html)
Question 7.25
I have a program which mallocs and later frees a lot of memory, but memory
usage (as reported by ps) doesn't seem to go back down.
A: Most implementations of malloc/free do not return freed memory to the
operating system (if there is one), but merely make it available for
future malloc calls within the same program.

On the other hand, if the space isn't being used by R it will be paged out
to virtual memory after a while, so it doesn't really matter whether it's
reclaimed (unless you are very short on virtual memory).


Thomas Lumley			Asst. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle

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