Rsync memory usage seems a lot higher than 100bytes/file
surerlistmail at gmail.com
Thu Jun 15 21:17:13 GMT 2006
On 6/15/06, Wayne Davison <wayned at samba.org> wrote:
> On Thu, Jun 15, 2006 at 11:50:52AM -0400, Surer Dink wrote:
> > Is this because I am using -H and --delete? What is the per-file
> > overhead when both of these options are used?
> It depends on what version of rsync you're using. Older versions would
> allocate an additional file list for --delete, and another for -H, so
> memory use is much more efficient in a modern version. Also, if your OS
> doesn't use copy-on-write memory when the receiver forks the generator,
> you'll see a doubling of the memory requirements on the receiving side.
I apologize not upgrading before sending the last mail - I carefully
checked the NEWS for all versions after the one I was using (2.6.6)
but saw no mention of memory usage reduction. I was reluctant to
upgrade because this is a critical production machine. After your
message I upgaded to 2.6.8 and indeed the memory usage has dropped
drastically and is now around 850MB on the rsync process.
FreeBSD certainly does copy-on-write after fork(), however when
running rsync I see two rsync processes, each with about 850MB
footprint. When starting, both processes slowly climb to 850MB, at
which point one proceed to chug along while the other process falls
asleep and gets swapped out. After a while the second process starts
growing slowly, reches approximately 150MB - aat this point I left for
a brief period of time, when I came back, the rsync was done.
Although I am quite happy that things "work" now, I still want to
confirm that in fact I should be seeing 2 rsync processes, both with
an 800MB footprint, and not just one. I suspect this is the case, but
just want a confirmation...
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