My summer with Google Summer of Code - 2018, Git organization.
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Google Summer of Code 2018 with Git


You can check out my proposal at this link.

Blogs posts:



git stash

This is what I have been working on during this summer. It is a series consisting of 26 patches. At the moment, they are on the mailing list, waiting to get reviewed. A part of them were already reviewed (up to and including "stash: convert store to builtin").


Link to every patch (mailing list)

* The project was originally started by Joel Teichroeb. During the bonding period, he agreed to give me custody of his patches (the ones marked with *). I independently modified the original patches and developed new ones.

Status: waiting to get reviewed


GitHub tag

Link to every patch (mailing list):

First series of patches:

Second series of patches:

Third series of patches:


When I started working on git stash, I did not forsee that get_oid() might die in case there is an empty reflog. The purpose of this patch is to replace spawning git rev-parse --verify --quiet.

GitHub pull request

GitHub tag

Mailing list

Link to every patch (mailing list)

Status: not merged


  • One thing which was not included in the schedule, but might be a welcomed feature, is to introduce a new subcommand: git stash commit which would act like git stash pop and git commit.

  • Add the possibility to see untracked files in a stash. There has been a discussion about this on the mailing list.

  • Running git stash show -p and trying to split a hunk does not work properly in all the cases. There has been a discussion about this on the mailing list

Initial file:


Case 1:

Case 2:

Running git stash push -p, splitting the hunk, accepting one and refusing the other one:

  • in the first case an error messaged is falsely (to some degree) displayed. The stash was created, but the changes were not removed from the index.

  • in the second case everything works fine.

So, the problem occurs only when there are 2 or less lines between the edited lines.


Running time on:

Linux (Ubuntu 17.10)

  • git test suite (,, and
        ** SHELL: 12,69s user 9,95s system 109% cpu 20,730 total
        **     C:  2,67s user 2,84s system 105% cpu  5,206 total
        ** SHELL: 1,43s user 0,94s system 106% cpu 2,242 total
        **     C: 1,01s user 0,58s system 104% cpu 1,530 total
        ** SHELL: 2,22s user 1,73s system 110% cpu 3,569 total
        **     C: 0,59s user 0,57s system 106% cpu 1,085 total
        ** SHELL: 2,89s user 2,99s system 106% cpu 5,527 total
        **     C: 2,21s user 2,61s system 105% cpu 4,568 total

        ** SHELL: 19.23s user 15.61s system
        **     C:  6.48s user  6.60s system
  • a git repository with 4000 files: 1000 not changed, 1000 staged files, 1000 unstaged files, 1000 untracked. In this case I ran some of the most used commands:

     git stash push:
     ** SHELL: 0,12s user 0,21s system 101% cpu 0,329 total
     **     C: 0,06s user 0,13s system 105% cpu 0,185 total
     git stash push -u:
     ** SHELL: 0,18s user 0,27s system  108% cpu 0,401 total
     **     C: 0,09s user 0,19s system  103% cpu 0,267 total
     git stash pop:
     ** SHELL: 0,16s user 0,26s system 103% cpu 0,399 total
     **     C: 0,13s user 0,19s system 102% cpu 0,308 total

Windows 8.1:

  • git test suite (,, and
        ** SHELL: 17m20.407s
        **    C:   5m 6.967s

        ** SHELL:
        real    11m28.043s
        user    0m11.042s
        sys     0m24.278s

        ** C:
        real    1m56.922s
        user    0m11.725s
        sys     0m25.462s

        ** SHELL:
        real    0m35.436s
        user    0m1.117s
        sys     0m2.669s

        ** C:
        real    0m32.015s
        user    0m2.346s
        sys     0m5.151s

        ** SHELL:
        real    2m11.608s
        user    0m2.482s
        sys     0m4.737s

        ** C:
        real    0m24.749s
        user    0m2.171s
        sys     0m5.060s

        ** SHELL:
        real    3m5.032s
        user    0m7.563s
        sys     0m21.697s

        ** C:
        real    2m13.281s
        user    0m8.644s
        sys     0m20.799s