Closed
Description
Describe the bug
On a clean checkout of a sizeable repo (~20k commits), the time for the first evaluation of a commit has recently increased by more than 10x (and an unhelpful message from Git is shown):
$ nix build # cache build
$ echo >> flake.nix; git commit -am foo
[fvis 296fea547d] foo
1 file changed, 1 insertion(+)
$ nix shell github:NixOS/nix/90b2dd570cbd8313a8cf45b3cf66ddef2bb06e07 -c sh -c 'nix --version; time nix build'
nix (Nix) 2.4pre20210902_90b2dd5
2.10user 0.59system 0:02.60elapsed 103%CPU (0avgtext+0avgdata 287372maxresident)k
0inputs+402536outputs (0major+115786minor)pagefaults 0swaps
$ echo >> flake.nix; git commit -am foo
[fvis 07a735a0b9] foo
1 file changed, 1 insertion(+)
$ nix shell github:NixOS/nix/6678e98411cd3bfe8143a4ba1b35d1451babce32 -c sh -c 'nix --version; time nix build'
nix (Nix) 2.4pre20210907_6678e98
hint: Using 'master' as the name for the initial branch. This default branch name
hint: is subject to change. To configure the initial branch name to use in all
hint: of your new repositories, which will suppress this warning, call:
hint:
hint: git config --global init.defaultBranch <name>
hint:
hint: Names commonly chosen instead of 'master' are 'main', 'trunk' and
hint: 'development'. The just-created branch can be renamed via this command:
hint:
hint: git branch -m <name>
94.89user 2.88system 0:35.60elapsed 274%CPU (0avgtext+0avgdata 1234872maxresident)k
264inputs+402224outputs (1major+488572minor)pagefaults 0swapsThis is due to #4922, which enables cloning submodules by default. But the submodules option is extremely inefficient, even if the repo does not even contain any submodules.
I know there has been some discussion on the PR itself after merging, but I felt that this regression deserved its own issue due to its severity.
Steps To Reproduce
git clone https://github.com/leanprover/lean4
cd lean4
nix flake prefetch
Expected behavior
A much faster store copy, as before
nix-env --version output
nix (Nix) 2.4pre20210907_6678e98