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When comparing large commit ranges (e.g., 250,000+ commits), range-diff attempts to allocate an n×n cost matrix that can exhaust available memory. For example, with 256,784 commits (n = 513,568), the matrix would require approximately 256GB of memory (513,568² × 4 bytes), causing either immediate segmentation faults due to integer overflow or system hangs. Add a memory limit check in get_correspondences() before allocating the cost matrix. This check uses the total size in bytes (n² × sizeof(int)) and compares it against a configurable maximum, preventing both excessive memory usage and integer overflow issues. The limit is configurable via a new --max-memory option that accepts human-readable sizes (e.g., "1G", "500M"). The default is 4GB for 64 bit systems and 2GB for 32 bit systems. This allows comparing ranges of approximately 32,000 (16,000) commits - generous for real-world use cases while preventing impractical operations. When the limit is exceeded, range-diff now displays a clear error message showing both the requested memory size and the maximum allowed, formatted in human-readable units for better user experience. Example usage: git range-diff --max-memory=1G branch1...branch2 git range-diff --max-memory=500M base..topic1 base..topic2 This approach was chosen over alternatives: - Pre-counting commits: Would require spawning additional git processes and reading all commits twice - Limiting by commit count: Less precise than actual memory usage - Streaming approach: Would require significant refactoring of the current algorithm This issue was previously discussed in: https://lore.kernel.org/git/RFC-cover-v2-0.5-00000000000-20211210T122901Z-avarab@gmail.com/ Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Paulo Casaretto <pcasaretto@gmail.com> 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.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc 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.adoc
(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 to git+subscribe@vger.kernel.org (see https://subspace.kernel.org/subscribing.html for details). The mailing list archives are available at https://lore.kernel.org/git/, https://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