Re: git svn forking an awful lot of "git config"s

[Eric Wong <normalperson@yhbt.net>]

Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
> Hi,
> 
> we are approaching our first release of msysGit's installer with git-svn.  
> However, I am experiencing a very bad performance, and an error:
> 
> $ git svn fetch
> trace: exec: 'git-svn' 'fetch'
> trace: built-in: git 'config' '--bool' '--get' 'svn.fetchall'
> trace: built-in: git 'config' '--get' 'svn.username'
> trace: built-in: git 'config' '--get' 'svn.repackflags'
> trace: built-in: git 'config' '--bool' '--get' 'svn.quiet'
> trace: built-in: git 'config' '--bool' '--get' 'svn.noauthcache'
> trace: built-in: git 'config' '--get' 'svn.revision'
> trace: built-in: git 'config' '--int' '--get' 'svn.repack'
> trace: built-in: git 'config' '--int' '--get' 'svn.logwindowsize'
> trace: built-in: git 'config' '--bool' '--get' 'svn.nocheckout'
> trace: built-in: git 'config' '--get' 'svn.configdir'
> trace: built-in: git 'config' '--bool' '--get' 'svn.noMetadata'
> trace: built-in: git 'config' '--bool' '--get' 'svn.useSvnsyncProps'
> trace: built-in: git 'config' '--bool' '--get' 'svn.followparent'
> trace: built-in: git 'config' '--get' 'svn.authorsfile'
> trace: built-in: git 'config' '--bool' '--get' 'svn.useSvmProps'
> trace: built-in: git 'config' '--bool' '--get' 'svn.uselogauthor'
> trace: built-in: git 'rev-parse' '--symbolic' '--all'
> trace: built-in: git 'config' '-l'
> trace: built-in: git 'config' '-l'
> trace: built-in: git 'config' '-l'
> trace: built-in: git 'config' '--int' '--get' 'svn-remote.svn.branches-maxRev'
> trace: built-in: git 'config' '--int' '--get' 'svn-remote.svn.tags-maxRev'
> trace: built-in: git 'config' '--get' 'svn-remote.svn.url'
> trace: built-in: git 'config' '--get' 'svn-remote.svn.uuid'
> trace: built-in: git 'config' 'svn-remote.svn.branches-maxRev' '8'
> could not lock config file
> config svn-remote.svn.branches-maxRev 8: command returned error: 255
> 
> I suspect that the locking problem is due to some strange anti-virus 
> interaction, because issuing the same command on the command line 
> succeeds.

I believe somebody on the list also had the same problem with file
locking in Windows.  Unfortunately, I have little idea as to what could
be wrong.  Could Windows not be releasing file locks properly?

It could be worth it to write a standalone Perl script that replicates
the git-config calls without the rest of git-svn getting in the way...

> However, did you notice the many calls to "git config"?  Especially the 
> three ones which list all values anyway?
> 
> I am not really sure if that is the single reason of the slowness -- 
> remember, Windows is mightily spawn()-challenged -- but it sure would help 
> to have git-svn read the config once at the beginning, probably with "-z", 
> too, and then just read from the cached values, no?

Many months ago, I thought about implementing a transparent caching layer
in Git.pm to work with git configs.  Of course, that requires
cooperation from all readers/writers within the process...  Done
correctly, it would help more than just git-svn. too.

I think I had this idea around the time we made git-config output Perl
hashes and arrays.

> Ciao,
> Dscho
> 
> P.S.: how far is the svn:external->submodule stuff?

Yikes.  I've let other work pile up on my ever-growing todo-list :/
I'll see if I can dig it out and wrap it up this weekend or next...

-- 
Eric Wong