git stash is slow on windows
WindowsGitGit BashGit StashWindows Problem Overview
On my windows machine git stash
has about 3.5 seconds overhead on each invocation, which adds about 7 seconds to my git commit hook.
The same command under linux (same machine) takes about 0.01 seconds. The performance issue applies to empty repositories as well.
I have tried the following from this thread and this thread:
core.fscache
is set totrue
core.preloadindex
is set totrue
gc.auto
is set to256
- Setting PS1='$ '
- Running cmd in administration mode
- Running inside cmd.exe instead of git-bash
Running GIT_TRACE=true git stash list
16:58:16.844591 git.c:563 trace: exec: 'git-stash' 'list'
16:58:16.844591 run-command.c:336 trace: run_command: 'git-stash' 'list'
16:58:19.699591 git.c:350 trace: built-in: git 'rev-parse' '--git-dir'
16:58:19.859591 git.c:350 trace: built-in: git 'rev-parse' '--git-path' 'objects'
16:58:20.069591 git.c:350 trace: built-in: git 'rev-parse' '--show-toplevel'
16:58:20.154591 git.c:350 trace: built-in: git 'rev-parse' '--git-path' 'index'
16:58:20.244591 git.c:350 trace: built-in: git 'config' '--get-colorbool' 'color.interactive'
16:58:20.334591 git.c:350 trace: built-in: git 'config' '--get-color' 'color.interactive.help' 'red bold'
16:58:20.424591 git.c:350 trace: built-in: git 'config' '--get-color' '' 'reset'
16:58:20.514591 git.c:350 trace: built-in: git 'rev-parse' '--verify' '--quiet' 'refs/stash'
real 0m3.845s
user 0m0.000s
sys 0m0.047s
Running GIT_TRACE_PERFORMANCE=true git stash list
16:59:18.414591 trace.c:420 performance: 0.001078046 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'rev-parse' '--git-dir'
16:59:18.569591 trace.c:420 performance: 0.000947184 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'rev-parse' '--git-path' 'objects'
16:59:18.779591 trace.c:420 performance: 0.001253627 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'rev-parse' '--show-toplevel'
16:59:18.869591 trace.c:420 performance: 0.001285517 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'rev-parse' '--git-path' 'index'
16:59:18.955591 trace.c:420 performance: 0.001139994 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'config' '--get-colorbool' 'color.interactive'
16:59:19.040591 trace.c:420 performance: 0.001182881 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'config' '--get-color' 'color.interactive.help' 'red bold'
16:59:19.125591 trace.c:420 performance: 0.001128997 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'config' '--get-color' '' 'reset'
16:59:19.215591 trace.c:420 performance: 0.001567766 s: git command: 'C:\Program Files\Git\mingw64\libexec\git-core\git.exe' 'rev-parse' '--verify' '--quiet' 'refs/stash'
16:59:19.295591 trace.c:420 performance: 3.730583540 s: git command: 'C:\Program Files\Git\mingw64\bin\git.exe' 'stash' 'list'
real 0m3.819s
user 0m0.000s
sys 0m0.062s
From the log we see that it takes around 3 seconds between the git-stash command is run and the git-rev-parse is run. Are there any other flags I can run to find the bottleneck?
Windows Solutions
Solution 1 - Windows
With Git for Windows 2.19 (Sept. 2018), git stash
(and git rebase
) are no longer script-only, but actually a binary compiled with git.exe
.
See git-for-windows/build-extra PR 203.
To activate them, type:
git config --global rebase.useBuiltin true
git config --global stash.useBuiltin true
Warning:
> As nice as the speed-ups are, the patches in question are still in flux, and they are not battle-tested at all.
So, for now, the script version of git stash
remains the default, that way:
> - users who want the raw speed improvement we got through three Google Summer of Code projects working in parallel can have that, > - while others who are reluctant to play guinea pig by running only well-tested code can stay on the safe side.
The point remains: in the next versions of Git, the bash script for git-stash
will eventually disappear, and its replacement is and will be faster.
Note: that next version will be Git 2.27 (Q2 2020): "git stash
" has kept an escape hatch to use the scripted version for a few releases, which got stale.
It has been removed.
See commit 8a2cd3f, commit b0c7362 (03 Mar 2020) by Thomas Gummerer (tgummerer
).
(Merged by Junio C Hamano -- gitster
-- in commit 369ae75, 27 Mar 2020)
> ## stash
: remove the stash.useBuiltin
setting
> Signed-off-by: Thomas Gummerer
> Remove the stash.useBuiltin
setting which was added as an escape hatch to disable the builtin version of stash first released with Git 2.22.
>
> Carrying the legacy version is a maintenance burden, and has in fact become out of date failing a test since the 2.23 release, without anyone noticing until now.
>
> So users would be getting a hint to fall back to a potentially buggy version of the tool.
>
> We used to shell out to git config
to get the useBuiltin
configuration to avoid changing any global state before spawning legacy-stash.
However that is no longer necessary, so just use the 'git_config
' function to get the setting instead.
>
> Similar to what we've done in d03ebd411c ("rebase
: remove the rebase.useBuiltin setting", 2019-03-18, Git v2.22.0-rc0 -- merge listed in batch #5), where we remove the corresponding setting for rebase, we leave the documentation in place, so people can refer back to it when searching for it online, and so we can refer to it in the commit message.
Update Q2 2019, with Git 2.22, git stash
is entirely rewritten in C.
²
See commit 40af146, commit 48ee24a, commit ef0f0b4, commit 64fe9c2, commit 1ac528c, commit d553f53, commit d4788af, commit 41e0dd5, commit dc7bd38, commit 130f269, commit bef55dc, commit dac566c, commit ab8ad46 (25 Feb 2019) by Paul-Sebastian Ungureanu (weekly-digest[bot]
).
See commit c4de61d, commit 577c199, commit 4e2dd39, commit 8a0fc8d (25 Feb 2019) by Joel Teichroeb (klusark
).
See commit 7906af0, commit 90a4627, commit 8d8e9c2 (25 Feb 2019) by Johannes Schindelin (dscho
).
(Merged by Junio C Hamano -- gitster
-- in commit e36adf7, 22 Apr 2019)
You can still use the shell script with git legacy-stash
.
And:
> ## stash
: convert stash--helper.c
into stash.c
> The old shell script git-stash.sh
was removed and replaced entirely by builtin/stash.c
.
In order to do that, create
and push
were adapted to work without stash.sh
.
>
> For example, before this commit, git stash create
called git stash--helper create --message "$*"
. If it called git stash--helper create "$@"
, then
some of these changes wouldn't have been necessary.
>
> This commit also removes the word helper
since now stash is
called directly and not by a shell script.
There are optimizations:
> ## stash
: optimize get_untracked_files()
and check_changes()
> This commits introduces a optimization by avoiding calling the
same functions again.
For example, git stash push -u
would call at some points the following functions:
>
> * check_changes()
(inside do_push_stash()
)
> * do_create_stash()
, which calls: check_changes()
and
get_untracked_files()
>
> Note that check_changes()
also calls get_untracked_files()
.
So, check_changes()
is called 2 times and get_untracked_files()
3 times.
>
> The old function check_changes()
now consists of two functions:
get_untracked_files()
and check_changes_tracked_files()
.
>
> These are the call chains for push
and create
:
>
> * push_stash()
-> do_push_stash()
-> do_create_stash()
> * create_stash()
-> do_create_stash()
>
> To prevent calling the same functions over and over again, check_changes()
inside do_create_stash()
is now placed in the caller functions (create_stash()
and do_push_stash()
).
This way check_changes()
and get_untracked files()
are called
only one time.
With Git 2.36 (Q2 2022), removal of the warning "the stash.useBuiltin support has been removed!
" is finally done!
See commit e9b272e, commit deeaf5e, commit 5d4dc38, commit 6de0722 (27 Jan 2022) by Johannes Schindelin (dscho
).
(Merged by Junio C Hamano -- gitster
-- in commit b9f791a, 16 Feb 2022)
> ## stash
: stop warning about the obsolete stash.useBuiltin
config setting
> Signed-off-by: Johannes Schindelin
> In 8a2cd3f ("stash
: remove the stash.useBuiltin setting", 2020-03-03, Git v2.27.0-rc0 -- merge listed in batch #2), we removed support for stash.useBuiltin
, but left a warning in its place.
>
> After almost two years, and several major versions, it is time to remove even that warning.
Solution 2 - Windows
git-stash
is a script, not a command compiled in the git.exe
binary.
On linux : I can find git-stash
at /usr/lib/git-core/git-stash
- I will let you look for the correct path on windows ...
This script uses #!/bin/sh
to run, I don't know what shell implementation is used when you run this on windows.
You can try to run it with another compatible shell (here: bash) :
# the git-core/ dir needs to be in the PATH,
# obviously you will need to provide the correct path for your git-core dir
$ PATH=/usr/lib/git-core:$PATH bash /usr/lib/git-core/git-stash
You can also turn the -x
flag, which will print a trace of all commands executed, and visually check if one of the sub commands seems to be the hanger :
$ PATH=/usr/lib/git-core:$PATH bash -x /usr/lib/git-core/git-stash