git-svn very slow on fetch (shared git-svn repo)

DISCUSSION Pascal Obry 2 participants 5 messages Jun 15, 2016

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Pascal Obry

author

2016-06-15 22:47 UTC #0 lore raw

Here is the problem.

Doing a:

   $ git svn fetch

Takes age to update the repository. The long story is that I'm trying to have shared git-svn repositories.

I'm cloning the repository on a server using a standard "git svn clone". I then let users cloning this repository using the procedure described in git-svn help. Copy/paste here:

<<
# Do the initial import on a server
ssh server "cd /pub && git svn clone
http://svn.example.com/project
# Clone locally - make sure the refs/remotes/ space matches the
server
mkdir project
cd project
git init
git remote add origin server:/pub/project git config --add remote.origin.fetch
'+refs/remotes/*:refs/remotes/*'
git fetch
# Create a local branch from one of the branches just fetched
git checkout -b master FETCH_HEAD
# Initialize 'git svn' locally (be sure to use the same URL and
-T/-b/-t options as were used on server)
git svn init http://svn.example.com/project
# Pull the latest changes from Subversion
git svn rebase

Quoted 1 line

Quoted 1 line

If you do a "git svn fetch" (to get new branches) it takes age if you have imported branches that are not used since a long time.

I've traced this down to the Perl fetch_all procedure. It seems that the fetch is looking at the older version in all branches and then read the remote repository starting from this revision. As some branches are unused since a very long it it re-read most of the history. In my example it start at rev 8200 whereas the last revision on trunk is 150000 (I put trace in git-svn Perl script).

I have observed that this happen only the first time.

This can be confirmed by the fact that if you break git-svn fetch process and restart it it will start to a later revision. So it seems that git-svn is keeping some kind of data about what has already been fetched but those data are not properly copied by the procedure above.

Is there a workaround that? Where are those data stored?

Any guidance would be very welcomed.

Thanks,
Pascal.

Signature · 8 lines

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
--|    http://www.obry.net  -  http://v2p.fr.eu.org
--| "The best way to travel is by means of imagination"
--|
--| gpg --keyserver keys.gnupg.net --recv-key F949BD3B

Eric Wong

2016-06-15 22:47 UTC #1 lore raw

Quoted 45 lines · Pascal Obry

Here is the problem.
Doing a:
   $ git svn fetch
Takes age to update the repository. The long story is that I'm trying to have shared git-svn repositories.
I'm cloning the repository on a server using a standard "git svn clone". I then let users cloning this repository using the procedure described in git-svn help. Copy/paste here:
<<
# Do the initial import on a server
ssh server "cd /pub && git svn clone
http://svn.example.com/project
# Clone locally - make sure the refs/remotes/ space matches the
server
mkdir project
cd project
git init
git remote add origin server:/pub/project git config --add remote.origin.fetch
'+refs/remotes/*:refs/remotes/*'
git fetch
# Create a local branch from one of the branches just fetched
git checkout -b master FETCH_HEAD
# Initialize 'git svn' locally (be sure to use the same URL and
-T/-b/-t options as were used on server)
git svn init http://svn.example.com/project
# Pull the latest changes from Subversion
git svn rebase
Quoted 1 line
Quoted 1 line
If you do a "git svn fetch" (to get new branches) it takes age if you have imported branches that are not used since a long time.
I've traced this down to the Perl fetch_all procedure. It seems that the fetch is looking at the older version in all branches and then read the remote repository starting from this revision. As some branches are unused since a very long it it re-read most of the history. In my example it start at rev 8200 whereas the last revision on trunk is 150000 (I put trace in git-svn Perl script).

Quoted 8 lines

I have observed that this happen only the first time.
This can be confirmed by the fact that if you break git-svn fetch process and restart it it will start to a later revision. So it seems that git-svn is keeping some kind of data about what has already been fetched but those data are not properly copied by the procedure above.
Is there a workaround that? Where are those data stored?

Hi Pascal,

For globs (branches and tags) the $GIT_DIR/svn/.metadata config file, under the svn-remote.svn.{branches,tags}-maxRev keys.

For explicitly specified refs (e.g. "trunk"), then it's in the last record of the corresponding rev_map (e.g. $GIT_DIR/svn/trunk/.rev_map.$UUID) as a 4-byte revision number + 20 bytes of zeroes.

Signature · 1 line

Eric Wong

Pascal Obry

author

2016-06-15 22:47 UTC #2 lore raw

Hi Eric,

Quoted 2 lines

For globs (branches and tags) the $GIT_DIR/svn/.metadata config file, under the svn-remote.svn.{branches,tags}-maxRev keys.

Right. I found out that copying the .metadata solve this problem.

Quoted 4 lines

For explicitly specified refs (e.g. "trunk"), then it's in the last record of the corresponding rev_map (e.g. $GIT_DIR/svn/trunk/.rev_map.$UUID) as a 4-byte revision number + 20 bytes of zeroes.

Seems like we do not need to copy this one as it is reconstructed by a simple rebase on the trunk branch. This is quite fast as reconstructed from the embedded git-svn-id if I'm not mistaken.

So you confirm that copying the .metadata is the solution?

Pascal.

Signature · 8 lines

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
--|    http://www.obry.net  -  http://v2p.fr.eu.org
--| "The best way to travel is by means of imagination"
--|
--| gpg --keyserver keys.gnupg.net --recv-key F949BD3B

Eric Wong

2016-06-15 22:47 UTC #3 lore raw

Quoted 12 lines · Pascal Obry

Hi Eric,
Quoted 2 lines
For globs (branches and tags) the $GIT_DIR/svn/.metadata config file, under the svn-remote.svn.{branches,tags}-maxRev keys.
Right. I found out that copying the .metadata solve this problem.
Quoted 4 lines
For explicitly specified refs (e.g. "trunk"), then it's in the last record of the corresponding rev_map (e.g. $GIT_DIR/svn/trunk/.rev_map.$UUID) as a 4-byte revision number + 20 bytes of zeroes.

Quoted 5 lines

Seems like we do not need to copy this one as it is reconstructed by a simple rebase on the trunk branch. This is quite fast as reconstructed from the embedded git-svn-id if I'm not mistaken.
So you confirm that copying the .metadata is the solution?

Yes, copying .metadata should be enough. The .rev_map rebuild should be fast.

Signature · 1 line

Eric Wong

Pascal Obry

author

2016-06-15 22:47 UTC #4 lore raw

Eric,

Quoted 1 line

Yes, copying .metadata should be enough.

I've put this in place. Works fine.

Quoted 1 line

The .rev_map rebuild should be fast.

Yep. Thanks for your quick reply.

Pascal.

Signature · 8 lines

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
--|    http://www.obry.net  -  http://v2p.fr.eu.org
--| "The best way to travel is by means of imagination"
--|
--| gpg --keyserver keys.gnupg.net --recv-key F949BD3B