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

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Feb 21, 2008, 00:18 UTC
Message-ID: <alpine.LSU.1.00.0802210006590.17164@racer.site>
In-Reply-To: <20080220223953.GA32663@hand.yhbt.net>

Him

On Wed, 20 Feb 2008, Eric Wong wrote:

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> Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
> 
> > 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?

I am not half as concerned with locks on Windows (since they occur regularly, thanks to _two_ Antiviruses, go figure), as with unnecessary config file reading.

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> > 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.

Yes, but I am really scared there. Last time, Pasky tried to put a _lot_ into Git.pm, and it did not work here. As a consequence, I put aside a _lot_ of my time to turn the most important (to me!) perl scripts into builtins.

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

You mean -z?

> > 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...

Actually, I can understand what you're talking about. But just let me tell this: I (amongst others) are _excited_ to wait until you have that particular feature working...

Ciao, Dscho