ab6eea6f7b
If you have an alternate object store with a very large number of refs, the peak memory usage of the sha1_array can grow high, even if most of them are duplicates that end up not being printed at all. The similar for_each_alternate_ref() code-paths in fetch-pack solve this by using flags in "struct object" to de-duplicate (and so are relying on obj_hash at the core). But we don't have a "struct object" at all in this case. We could call lookup_unknown_object() to get one, but if our goal is reducing memory footprint, it's not great: - an unknown object is as large as the largest object type (a commit), which is bigger than an oidset entry - we can free the memory after our ref advertisement, but "struct object" entries persist forever (and the receive-pack may hang around for a long time, as the bottleneck is often client upload bandwidth). So let's use an oidset. Note that unlike a sha1-array it doesn't sort the output as a side effect. However, our output is at least stable, because for_each_alternate_ref() will give us the sha1s in ref-sorted order. In one particularly pathological case with an alternate that has 60,000 unique refs out of 80 million total, this reduced the peak heap usage of "git receive-pack . </dev/null" from 13GB to 14MB. 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 http://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-.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). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.org/git, http://marc.info/?l=git and other archival sites.
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