threads / bug / 45593

Bug? git submodule update --reference doesn't use the referenced repository

Subject: Bug? git submodule update --reference doesn't use the referenced repository

## tl;dr

3 messages between Apr 3, 2017 and Apr 4, 2017.

replies: 2people: 2as markdown or json

Maxime Viargues· Apr 3, 2017, 03:13 UTC · lore
Hi there,

I have been trying to use the --reference option to clone a big repository using a local copy, but I can't manage to make it work using sub-module update. I believe this is a bug, unless I missed something. I am on Windows, Git 2.12.0

So the problem is as follow:
- I have got a repository with multiple sub-modules, say
     main
         lib1
             sub-module1.git
         lib2
             sub-module2.git
- The original repositories are in GitHub, which makes it slow
- I have done a normal git clone of the entire repository (not bare) and 
put it on a file server, say \\fileserver\ref_repo\
(Note that the problem also happens with local copy)

So if I do a clone to get the repo and all the submodules with... git clone --reference-if-able \\fileserver\ref-repo --recursive git@github.com:company/main ...then it all works, all the sub-modules get cloned and the it's fast.

Now in my case I am working with Jenkins jobs and I need to first do a clone, and then get the sub-modules, but if I do... git clone --reference-if-able \\fileserver\ref-repo git@github.com:company/main (so non-recursive) cd main git submodule update --init --reference \\fileserver\ref-repo ... then this takes ages, as it would normally do without the use of --reference. I suspect it's not actually using it. The git clone documentation mentions that the reference is then passed to the sub-module clone commands, so I would expect "git clone --recursive" to work the same as "git submodule update", as far as --reference is concerned.

I noticed for a single module, doing a... git submodule update --init --reference \\fileserver\ref-repo\lib1\sub-module1 -- lib1/sub-module1 ...i.e. adding the sub-module path to the reference path, works. Which kind of make sense but then how do you do to apply it to all the sub-modules? (without writing a script to do that)

If someone can confirm the problem or explain me what I am dong wrong that would be great.

Maxime
Stefan Beller· Apr 3, 2017, 16:32 UTC · re: Maxime Viargues · lore

Re: Bug? git submodule update --reference doesn't use the referenced repository

On Sun, Apr 2, 2017 at 8:13 PM, Maxime Viargues <maxime.viargues@serato.com> wrote:

Show 6 quoted lines
> Hi there,
>
> I have been trying to use the --reference option to clone a big repository
> using a local copy, but I can't manage to make it work using sub-module
> update. I believe this is a bug, unless I missed something.
> I am on Windows, Git 2.12.0
which is new enough, that the new --reference code is in. :)
Show 17 quoted lines
>
> So the problem is as follow:
> - I have got a repository with multiple sub-modules, say
>     main
>         lib1
>             sub-module1.git
>         lib2
>             sub-module2.git
> - The original repositories are in GitHub, which makes it slow
> - I have done a normal git clone of the entire repository (not bare) and put
> it on a file server, say \\fileserver\ref_repo\
> (Note that the problem also happens with local copy)
>
> So if I do a clone to get the repo and all the submodules with...
> git clone --reference-if-able \\fileserver\ref-repo --recursive
> git@github.com:company/main
> ...then it all works, all the sub-modules get cloned and the it's fast.
great. :)
Show 8 quoted lines
> Now in my case I am working with Jenkins jobs and I need to first do a
> clone, and then get the sub-modules, but if I do...
> git clone --reference-if-able \\fileserver\ref-repo
> git@github.com:company/main (so non-recursive)
> cd main
> git submodule update --init --reference \\fileserver\ref-repo
> ... then this takes ages, as it would normally do without the use of
> --reference. I suspect it's not actually using it.
So to confirm your suspicion, can you run
  GIT_TRACE=1 git clone ...
  cd main && GIT_TRACE=1 git submodule update ...

to see which child processes are spawned to deal with the submodules? Also to confirm, it is the "submodule update" that is taking so long for you?

> The git clone documentation mentions that the reference is then passed to
> the sub-module clone commands, so I would expect "git clone --recursive" to
> work the same as "git submodule update", as far as --reference is concerned.
Oh, there we have an opportunity to improve the man page (or the code).
    git clone --reference --recursive ...
will set the config variables
    git config submodule.alternateLocation superproject
    git config submodule.alternateErrorStrategy die (or "info" for
--reference-if-able)

and the clone for the submodules (that are an independent process, just run after the clone of the superproject is done) will pickup these config variables and act accordingly.

If you only run
    git clone --reference ...

then these variables are not set. Probably they should be set such that the later invocation of "git submodule update --int" will behave the same as the git-clone of the superproject did.

So as a workaround for you to get up to speed again, you can just set these config variables yourself before running the "submodule update --init" and it should work.

Show 7 quoted lines
>
> I noticed for a single module, doing a...
> git submodule update --init --reference
> \\fileserver\ref-repo\lib1\sub-module1 -- lib1/sub-module1
> ...i.e. adding the sub-module path to the reference path, works. Which kind
> of make sense but then how do you do to apply it to all the sub-modules?
> (without writing a script to do that)

I think that functionality is broken as it takes the same reference for all submodules, such that you need to go through the submodules one by one and give the submodule specific reference location.

Show 5 quoted lines
>
> If someone can confirm the problem or explain me what I am dong wrong that
> would be great.
>
> Maxime
Stefan
Maxime Viargues· Apr 4, 2017, 02:15 UTC · re: Stefan Beller · lore

Re: Bug? git submodule update --reference doesn't use the referenced repository

On 04-Apr-17 4:32 AM, Stefan Beller wrote:
Show 43 quoted lines
> On Sun, Apr 2, 2017 at 8:13 PM, Maxime Viargues
> <maxime.viargues@serato.com> wrote:
>> Hi there,
>>
>> I have been trying to use the --reference option to clone a big repository
>> using a local copy, but I can't manage to make it work using sub-module
>> update. I believe this is a bug, unless I missed something.
>> I am on Windows, Git 2.12.0
> which is new enough, that the new --reference code is in. :)
>
>> So the problem is as follow:
>> - I have got a repository with multiple sub-modules, say
>>      main
>>          lib1
>>              sub-module1.git
>>          lib2
>>              sub-module2.git
>> - The original repositories are in GitHub, which makes it slow
>> - I have done a normal git clone of the entire repository (not bare) and put
>> it on a file server, say \\fileserver\ref_repo\
>> (Note that the problem also happens with local copy)
>>
>> So if I do a clone to get the repo and all the submodules with...
>> git clone --reference-if-able \\fileserver\ref-repo --recursive
>> git@github.com:company/main
>> ...then it all works, all the sub-modules get cloned and the it's fast.
> great. :)
>
>> Now in my case I am working with Jenkins jobs and I need to first do a
>> clone, and then get the sub-modules, but if I do...
>> git clone --reference-if-able \\fileserver\ref-repo
>> git@github.com:company/main (so non-recursive)
>> cd main
>> git submodule update --init --reference \\fileserver\ref-repo
>> ... then this takes ages, as it would normally do without the use of
>> --reference. I suspect it's not actually using it.
> So to confirm your suspicion, can you run
>
>    GIT_TRACE=1 git clone ...
>    cd main && GIT_TRACE=1 git submodule update ...
>
> to see which child processes are spawned to deal with the submodules?
> Also to confirm, it is the "submodule update" that is taking so long for you?

Yes I confirm it's the "submodule update" which is taking a long time. The clone with the reference is definitely working.

Running git submodule update with "GIT_TRACE=1", here is a snippet of what I get:

10:14:44.924684 git.c:596 trace: exec: 'git-submodule' 'update' '--init' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:14:44.925684 run-command.c:369 trace: run_command: 'git-submodule' 'update' '--init' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:14:45.146488 git.c:596 trace: exec: 'git-sh-i18n--envsubst' '--variables' 'usage: $dashless $USAGE' 10:14:45.146488 run-command.c:369 trace: run_command: 'git-sh-i18n--envsubst' '--variables' 'usage: $dashless $USAGE' 10:14:45.231548 git.c:596 trace: exec: 'git-sh-i18n--envsubst' 'usage: $dashless $USAGE' 10:14:45.231548 run-command.c:369 trace: run_command: 'git-sh-i18n--envsubst' 'usage: $dashless $USAGE' 10:14:45.357059 git.c:371 trace: built-in: git 'rev-parse' '--git-dir' 10:14:45.427806 git.c:371 trace: built-in: git 'rev-parse' '--git-path' 'objects' 10:14:45.487348 git.c:371 trace: built-in: git 'rev-parse' '-q' '--git-dir' 10:14:45.593794 git.c:371 trace: built-in: git 'rev-parse' '--show-prefix' 10:14:45.643162 git.c:371 trace: built-in: git 'rev-parse' '--show-toplevel' 10:14:45.700201 git.c:371 trace: built-in: git 'submodule--helper' 'init' 10:14:45.986024 git.c:371 trace: built-in: git 'submodule--helper' 'update-clone' '--reference=\\fileserver\Builds\reference_repos\main-repo' 10:14:45.988024 run-command.c:1155 run_processes_parallel: preparing to run up to 1 tasks 10:14:45.988024 run-command.c:369 trace: run_command: 'submodule--helper' 'clone' '--path' 'lib1/lib1_source' '--name' 'lib1/lib1_source' '--url' 'git@github.com:company/main-repo-lib1.git' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:15:06.204872 run-command.c:369 trace: run_command: 'submodule--helper' 'clone' '--path' 'lib2/lib2_source' '--name' 'lib2/lib2_source' '--url' 'git@github.com:company/main-repo-lib2.git' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:14:46.025555 git.c:371 trace: built-in: git 'submodule--helper' 'clone' '--path' 'lib1/lib1_source' '--name' 'lib1/lib1_source' '--url' 'git@github.com:company/main-repo-lib1.git' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:14:46.027555 run-command.c:369 trace: run_command: 'clone' '--no-checkout' '--reference' '\\fileserver\Builds\reference_repos\main-repo' '--separate-git-dir' 'D:/tmp2/git_clone_tests/main-repo/.git/modules/lib1/lib1_source' 'git@github.com:company/main-repo-lib1.git' 'D:/tmp2/git_clone_tests/main-repo/lib1/lib1_source' 10:14:46.061305 git.c:371 trace: built-in: git 'clone' '--no-checkout' '--reference' '\\fileserver\Builds\reference_repos\main-repo' '--separate-git-dir' 'D:/tmp2/git_clone_tests/main-repo/.git/modules/lib1/lib1_source' 'git@github.com:company/main-repo-lib1.git' 'D:/tmp2/git_clone_tests/main-repo/lib1/lib1_source' 10:14:46.115339 run-command.c:369 trace: run_command: 'ssh' 'git@github.com' 'git-upload-pack '\''company/main-repo-lib1.git'\''' Cloning into 'D:/tmp2/git_clone_tests/main-repo/lib1/lib1_source'... 10:14:48.962590 run-command.c:369 trace: run_command: 'git-upload-pack '\''//fileserver/Builds/reference_repos/main-repo/.git'\''' 10:14:49.103908 run-command.c:369 trace: run_command: 'git-upload-pack '\''D:/GitHub/main-repo/.git'\''' 10:14:49.184477 run-command.c:369 trace: run_command: 'git-upload-pack '\''//fileserver/Builds/reference_repos/main-repo/.git'\''' 10:14:49.322365 run-command.c:369 trace: run_command: 'git-upload-pack '\''D:/GitHub/main-repo/.git'\''' 10:14:52.281044 run-command.c:369 trace: run_command: 'index-pack' '--stdin' '--fix-thin' '--keep=fetch-pack 5764 on WIN-1198' '--check-self-contained-and-connected' 10:14:52.315569 git.c:371 trace: built-in: git 'index-pack' '--stdin' '--fix-thin' '--keep=fetch-pack 5764 on WIN-1198' '--check-self-contained-and-connected' 10:15:06.119340 run-command.c:369 trace: run_command: 'rev-list' '--objects' '--stdin' '--not' '--all' '--quiet' 10:15:06.170876 git.c:371 trace: built-in: git 'rev-list' '--objects' '--stdin' '--not' '--all' '--quiet' 10:15:13.072336 run-command.c:369 trace: run_command: 'submodule--helper' 'clone' '--path' 'lib3/lib3_source' '--name' 'lib3/lib3_source' '--url' 'git@github.com:company/main-repo-lib3' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:15:06.238893 git.c:371 trace: built-in: git 'submodule--helper' 'clone' '--path' 'lib2/lib2_source' '--name' 'lib2/lib2_source' '--url' 'git@github.com:company/main-repo-lib2.git' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:15:06.239894 run-command.c:369 trace: run_command: 'clone' '--no-checkout' '--reference' '\\fileserver\Builds\reference_repos\main-repo' '--separate-git-dir' 'D:/tmp2/git_clone_tests/main-repo/.git/modules/lib2/lib2_source' 'git@github.com:company/main-repo-lib2.git' 'D:/tmp2/git_clone_tests/main-repo/lib2/lib2_source' 10:15:06.273418 git.c:371 trace: built-in: git 'clone' '--no-checkout' '--reference' '\\fileserver\Builds\reference_repos\main-repo' '--separate-git-dir' 'D:/tmp2/git_clone_tests/main-repo/.git/modules/lib2/lib2_source' 'git@github.com:company/main-repo-lib2.git' 'D:/tmp2/git_clone_tests/main-repo/lib2/lib2_source' 10:15:06.309945 run-command.c:369 trace: run_command: 'ssh' 'git@github.com' 'git-upload-pack '\''company/main-repo-lib2.git'\''' Cloning into 'D:/tmp2/git_clone_tests/main-repo/lib2/lib2_source'... 10:15:08.210491 run-command.c:369 trace: run_command: 'git-upload-pack '\''//fileserver/Builds/reference_repos/main-repo/.git'\''' 10:15:08.370561 run-command.c:369 trace: run_command: 'git-upload-pack '\''D:/GitHub/main-repo/.git'\''' 10:15:08.451234 run-command.c:369 trace: run_command: 'git-upload-pack '\''//fileserver/Builds/reference_repos/main-repo/.git'\''' 10:15:08.589129 run-command.c:369 trace: run_command: 'git-upload-pack '\''D:/GitHub/main-repo/.git'\''' 10:15:11.533328 run-command.c:369 trace: run_command: 'index-pack' '--stdin' '--fix-thin' '--keep=fetch-pack 9308 on WIN-1198' '--check-self-contained-and-connected' 10:15:11.575862 git.c:371 trace: built-in: git 'index-pack' '--stdin' '--fix-thin' '--keep=fetch-pack 9308 on WIN-1198' '--check-self-contained-and-connected' 10:15:12.986776 run-command.c:369 trace: run_command: 'rev-list' '--objects' '--stdin' '--not' '--all' '--quiet' 10:15:13.039314 git.c:371 trace: built-in: git 'rev-list' '--objects' '--stdin' '--not' '--all' '--quiet' 10:15:49.633796 run-command.c:369 trace: run_command: 'submodule--helper' 'clone' '--path' 'lib4/lib4_source' '--name' 'lib4/lib4_source' '--url' 'git@github.com:company/main-repo-lib4.git' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:15:13.106441 git.c:371 trace: built-in: git 'submodule--helper' 'clone' '--path' 'lib3/lib3_source' '--name' 'lib3/lib3_source' '--url' 'git@github.com:company/main-repo-lib3' '--reference' '\\fileserver\Builds\reference_repos\main-repo' 10:15:13.107441 run-command.c:369 trace: run_command: 'clone' '--no-checkout' '--reference' '\\fileserver\Builds\reference_repos\main-repo' '--separate-git-dir' 'D:/tmp2/git_clone_tests/main-repo/.git/modules/lib3/lib3_source' 'git@github.com:company/main-repo-lib3' 'D:/tmp2/git_clone_tests/main-repo/lib3/lib3_source' 10:15:13.141464 git.c:371 trace: built-in: git 'clone' '--no-checkout' '--reference' '\\fileserver\Builds\reference_repos\main-repo' '--separate-git-dir' 'D:/tmp2/git_clone_tests/main-repo/.git/modules/lib3/lib3_source' 'git@github.com:company/main-repo-lib3' 'D:/tmp2/git_clone_tests/main-repo/lib3/lib3_source' 10:15:13.174486 run-command.c:369 trace: run_command: 'ssh' 'git@github.com' 'git-upload-pack '\''company/main-repo-lib3'\''' ...

Show 32 quoted lines
>
>> The git clone documentation mentions that the reference is then passed to
>> the sub-module clone commands, so I would expect "git clone --recursive" to
>> work the same as "git submodule update", as far as --reference is concerned.
> Oh, there we have an opportunity to improve the man page (or the code).
>
>      git clone --reference --recursive ...
>
> will set the config variables
>
>      git config submodule.alternateLocation superproject
>      git config submodule.alternateErrorStrategy die (or "info" for
> --reference-if-able)
>
> and the clone for the submodules (that are an independent process, just
> run after the clone of the superproject is done) will pickup these
> config variables
> and act accordingly.
>
> If you only run
>
>      git clone --reference ...
>
> then these variables are not set. Probably they should be set such
> that the later
> invocation of "git submodule update --int" will behave the same as the git-clone
> of the superproject did.
>
> So as a workaround for you to get up to speed again, you can just set
> these config
> variables yourself before running the "submodule update --init" and it
> should work.
Ok I'll try that.
Show 10 quoted lines
>> I noticed for a single module, doing a...
>> git submodule update --init --reference
>> \\fileserver\ref-repo\lib1\sub-module1 -- lib1/sub-module1
>> ...i.e. adding the sub-module path to the reference path, works. Which kind
>> of make sense but then how do you do to apply it to all the sub-modules?
>> (without writing a script to do that)
> I think that functionality is broken as it takes the same reference
> for all submodules,
> such that you need to go through the submodules one by one and give the
> submodule specific reference location.

I actually made a script to run it on each submodule, which works but is still quite slow as it cannot be parallelized (git doesn't like multiple submodule updates running concurrently).

Show 6 quoted lines
>
>> If someone can confirm the problem or explain me what I am dong wrong that
>> would be great.
>>
>> Maxime
> Stefan
Thanks for you quick answer
Maxime

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