2000-11-02-15:17:27 Andy Small:
> I searched the archive of last 3 months of this list for a FAQ
> posting, but I could not find one.
I haven't seen such a document, but this mailing list seems to work
pretty well, and the repetition rate I've seen hasn't been enough to
drive me to FAQ.
> Where does rsync store the filelist that it builds?
I wouldn't call this one an FAQ, not yet anyway. The file list is in
memory; space required to run rsync grows linearly in the number of
files in the directory heirarchy to be copied, and the whole thing
is built in memory before the copying starts. This can be a
performance hit in some settings. There's been discussion about
doing away with this, letting rsync work through something like a
depth-first sorted-order traversal or some such, both ends could do
that in synch, with memory requirements often down to O(logN) from
O(N), but as far as I know it hasn't progressed beyond
talk; presumably, nobody with the expertise and tuits to try to
tackle the coding is severely inconvenienced by the performance
consequences of the current implementation.
> When you fork off rsync processes in rapid succession, does
> it have to build the list for each process?
Yup.
> Say you want to sync from ONE source server to FIVE destination
> servers, and you have PERL doing the process management portion
> (i.e. forking, waiting, etc...).
There will be 5 complete scans of the whole src tree done, building
5 in-memory data structures representing the entire tree, and if the
first one started hasn't finished before the last one gets far
enough along to start the actual copying, all 5 will be in VM at
once.
Sorry for all the bad news.
-Bennett
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