Bug report. Out of memory about git checkout.

[void f <fv729164860@gmail.com>]

How to repeat:

env:

git version: 2.36.1
os : center os
memory 8G

When you execute "git checkout .” to chekout a very large lfs-file,
Which is larger than your memory. It would throw “Out of memory,
realloc failed” exception.


reason of the bug:


When you execute git checkout, Which have to checkout a lfs-file to
the worktree. Git would execute "convert.c apply_multi_file_filter()"
to convert lfs pointer from git-object to the lfs file. It will
execute a subprocess to convert this file. But It is strange that git
would read all of the file into memory When finish the git-lfs
subprocess. (The code is about pkt-line.c
read_packetized_to_strbut()). Lfs usually is a very large file even
more than the memory. So it would throw out of memory exception.

With this bug, it would have trouble to use sparse-chekout in a
repository with large lfs-file. Because you must init the repository
first and set the sparse-chekout config, than use git
pull/merge/checkout to checkout your subset worktree. It would out of
memory when you checkout it.

I think git don’t need to read all of the file in memory. It can use a
stream to finish the checkout.