51b27747e5
If the global variable "save_commit_buffer" is set to 0, then parse_commit() will throw away the commit object data after parsing it, rather than sticking it into a commit slab. This goes all the way back to60ab26de99([PATCH] Avoid wasting memory in git-rev-list, 2005-09-15). But there's another code path which may similarly stash the buffer: parse_object_buffer(). This is where we end up if we parse a commit via parse_object(), and it's used directly in a few other code paths like git-fsck. The original goal of60ab26de99was avoiding extra memory usage for rev-list. And there it's not all that important to catch parse_object(). We use that function only for looking at the tips of the traversal, and the majority of the commits are parsed by following parent links, where we use parse_commit() directly. So we were wasting some memory, but only a small portion. It's much easier to see the effect with fsck. Since we now turn off save_commit_buffer by default there, we _should_ be able to drop the freeing of the commit buffer in fsck_obj(). But if we do so (taking the first hunk of this patch without the rest), then the peak heap of "git fsck" in a clone of git.git goes from 136MB to 194MB. Teaching parse_object_buffer() to respect save_commit_buffer brings that down to 134.5MB (it's hard to tell from massif's output, but I suspect the savings comes from avoiding the overhead of the mostly-empty commit slab). Other programs should see a small improvement. Both "rev-list --all" and "fsck --connectivity-only" improve by a few hundred kilobytes, as they'd avoid loading the tip objects of their traversals. Most importantly, no code should be hurt by doing this. Any program that turns off save_commit_buffer is already making the assumption that any commit it sees may need to have its object data loaded on demand, as it doesn't know which ones were parsed by parse_commit() versus parse_object(). Not to mention that anything parsed by the commit graph may be in the same boat, even if save_commit_buffer was not disabled. This should be the only spot that needs to be fixed. Grepping for set_commit_buffer() shows that this and parse_commit() are the only relevant calls. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org (not the Git list). The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks