On Wed, Sep 15, 2021 at 10:50:57PM -0700, Matt Roper wrote:
What did you do before the bug happened? (Steps to reproduce your issue)
I activated split index mode on a repo ("git config core.splitIndex
true"), performed an interactive rebase, modified a commit earlier in
the history.
The steps can be reproduced via a sequence of:
$ mkdir tmp && cd tmp && git init
$ git config core.splitIndex true
$ for x in `seq 20`; do echo $x >> count; git add count; git commit -m "Commit $x"; done
$ git rebase -i HEAD~10
## Add "x git commit --amend --no-edit" as the first command of
## the todo list.
What did you expect to happen? (Expected behavior)
My expectation was that there would still only be a single shared index
file in the .git directory upon completion of the rebase.
What happened instead? (Actual behavior)
A large number of distinct sharedindex.* files were generated in the .git
directory during the rebase.
Probably relevant to the debug, but I still didn't figure out the cause. This
works ok and only one .sharedindex is created
git config core.splitIndex true
git am 000[123].patch
git config core.splitIndex false
Prepare test:
git config core.splitIndex false
git update-index --no-split-index
rm .git/sharedindex.*
git reset --hard HEAD~3
git -c core.splitIndex=true am 000[123].patch
This will create 4 .git/sharedindex.* files.
Then it will create 1 .git/shareindex.* file per call to status if the
current head doesn't match the previous and the splitIndex doesn't match
the previous. This keeps increasing:
git reset --hard ORIG_HEAD; git -c core.splitIndex=true status; ls -l .git/sharedindex.* | wc -l
...
4
git reset --hard ORIG_HEAD; git -c core.splitIndex=true status; ls -l .git/sharedindex.* | wc -l
...
5
...
note that if I pass -c core.splitIndex=true to git reset, this behavior
goes away. It seems that somehow the setting splitindex is getting reset
during git-am with multiple patches (or during rebase)... ?
Lucas De Marchi
What's different between what you expected and what actually happened?
Rather than a single shared index file, I wound up with a huge number of
large shared index files. The real repository I was working with (a Linux
kernel source tree) had a shared index file size of about 7MB, and I was
modifying a commit several hundred back in history (in case it
matters, these were all linear commits, no merges), so the resulting
collection of shared index files consumed a surprising amount of disk
space.
Anything else you want to add:
As an experiment, I tried setting splitIndex.sharedIndexExpire=now to see
if it would avoid the explosion of shared index files, but it appears the
stale index files are still not being removed during the rebase, and I
still wind up with a huge number at the end of the rebase. If I manually
run "git update-index --split-index" after the rebase completes it will
properly delete all of the stale ones at that point.
Rebases that do not actually modify the history do _not_ trigger the
explosion of shared index files (e.g., "git rebase -i HEAD~10 --exec 'echo
foo'").
If I do not set the core.splitIndex setting on the repository, but only
activate split index manually via "git update-index --split-index" there
is only one shared index file at the end of the rebase, but based on the
file size it appears the repository is no longer operating in split index
mode.
Before:
$ ll .git | grep index
-rw-rw-r-- 1 mdroper mdroper 149165 Sep 15 22:21 index
-rw-rw-r-- 1 mdroper mdroper 7296080 Sep 15 22:21 sharedindex.f916dd59ccc22ca34298f557a4659aca2767dae4
After (just amending HEAD~1 in this case):
$ ls -l .git | grep index
-rw-rw-r-- 1 mdroper mdroper 7445145 Sep 15 22:22 index
-rw-rw-r-- 1 mdroper mdroper 7296080 Sep 15 22:22 sharedindex.f916dd59ccc22ca34298f557a4659aca2767dae4
[System Info]
git version:
git version 2.33.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Linux 5.8.18-100.fc31.x86_64 #1 SMP Mon Nov 2 20:32:55 UTC 2020 x86_64
compiler info: gnuc: 9.3
libc info: glibc: 2.30
$SHELL (typically, interactive shell): /bin/bash
[Enabled Hooks]
--
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
(916) 356-2795
