git annotate runs out of memory

["Daniel Berlin" <dberlin@dberlin.org>]

On the gcc repository (which is now a 234 meg pack for me), git
annotate ChangeLog takes > 800 meg of memory (I stopped it at about
1.6 gig, since it started swapping my machine).
I assume it will run out of memory.  I stopped it after 2 minutes.

Mercurial, on the same file, takes 50 meg and 30 seconds.


git annotate fold-const.c takes 300 meg of memory and takes > 30 seconds.
Mercurial, on the same file takes 50 meg of memory and 10 seconds.
svn takes 15 seconds and 20 meg of memory.

I have excluded the mmap memory from mmap'ing the pack/file (in
git/mercurial respectively).

Annotate is treasured by gcc developers (this was a key sticking point
in svn conversion).
Having an annotate that is 2x slower and takes 15x memory would not
fly (regardless of how good the results are).

This seems to be a common problem with git. It seems to use a lot of
memory to perform common operations on the gcc repository (even though
it is faster in some cases than hg).

--Dan