Re: Move to git is imminent - awaiting Stefan's approval

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 08 Jan 2014 22:55:21 +0100
> From: Angelo Graziosi <angelo.graziosi@alice.it>
> CC: schwab@suse.de, stephen.berman@gmx.net, sven.axelsson@gmail.com, 
>  emacs-devel@gnu.org
> 
> Il 08/01/2014 18.32, Eli Zaretskii ha scritto:
> >> Date: Tue, 07 Jan 2014 21:08:51 +0100
> >> From: Angelo Graziosi <angelo.graziosi@alice.it>
> >> CC: stephen.berman@gmx.net, sven.axelsson@gmail.com, emacs-devel@gnu.org
> >>
> >> $ cd emacs.git/
> >> $ git gc --aggressive
> >> Counting objects: 735546, done.
> >> Delta compression using up to 2 threads.
> >> Compressing objects: 100% (734446/734446), done.
> >> Writing objects: 100% (735546/735546), done.
> >> Total 735546 (delta 589814), reused 143177 (delta 0)
> >> Checking connectivity: 735546, done.
> >>
> >> which took almost 3 hours to be completed.
> >>
> >> And the size is:
> >>
> >> $ cd ..
> >>
> >> $ du -s emacs.git/
> >> 327M	emacs.git/
> >>
> >> which seems very good!
> >
> > I guess this was on Windows 7, right?  I succeeded to do this on a
> 
> NO!! It is on Win XP 32 bit (SP3) with AMD Athlon 64 X2 Dual Core 
> Processor 3800+ and 1.7GiB of RAM.

The secret that unlocked this mystery was this:

> >> Delta compression using up to 2 threads.
                                   ^^^^^^^^^
On my machine, which is a Core i7, this originally said "8 threads".
So I did this: 

  git config --global pack.threads "2"

then ran "git gc --aggressive" again.  That again ran out of memory,
but much later in the process.  The next step was obvious:

  git config --global pack.threads "1"

With that, "git gc --aggressive" churned away for a little bit more
than an hour, and brought me to this:

  $ du -sh .
  323M    .

> > 64-bit Windows 7 as well, and it took about 2 hours.  And now I
> > understand why git ran out of memory on Windows XP: the memory
> > footprint of git-pack-objects goes up to 3GB, whereas Windows XP has
> > only 3GB address space for all the applications.
> 
> Here, on XP, Task Manager shows a memory usage under 1500 MiB (about 1.4 
> GiB)

With 1 thread, it never goes above 850MB.