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On Debian-alikes, POSIX sh has a hardcoded recursion depth
of 1000. This limit operates like bash's `$FUNCNEST` [1], but
it does not actually respect `$FUNCNEST`. This is non-standard
behavior. On other distros, the sh recursion depth is limited
only by the available stack size.
With certain history graphs, subtree splits are recursive—with
one recursion per commit. Attempting to split complex repos that
have thousands of commits, like [2], may fail on these distros.
Reduce the amount of recursion required by eagerly discovering
the complete range of commits to process.
The recursion is a side-effect of the rejoin-finder in
`find_existing_splits`. Rejoin mode, as in
git subtree split --rejoin -b hax main ...
improves the speed of later splits by merging the split history
back into `main`. This gives the splitting algorithm a stopping
point. The rejoin maps one commit on `main` to one split commit
on `hax`. If we encounter this commit, we know that it maps to
`hax`.
But this is only a single point in the history. Many splits
require history from before the rejoin. See patch content for
examples.
If pre-rejoin history is required, `check_parents` recursively
discovers each individual parent, with one recursion per commit.
The recursion deepens the entire tree, even if an older rejoin
is available. This quickly overwhelms the Debian sh stack.
Instead of recursively processing each commit, process *all* the
commits back to the next obvious starting point: i.e., either the
next-oldest --rejoin or the beginning of history. This is where the
recursion is likely to stop anyway.
While this still requires recursion, it is *considerably* less
recursive.
[1]: https://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html#index-FUNCNEST
[2]: https://github.com/christian-heusel/aur.git
Signed-off-by: Colin Stagner <ask+git@howdoi.land>
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