[patch] git svn slowness on win32

[patch] git svn slowness on win32

[josh robb]

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Hi,

I'm using git svn (1.6.4.msysgit.0) within a WindowsXP VM running
under VMWare fusion on OSX 10.5. For me (and at least one other person
I know) git svn has been unbearably slow.

My profiling shows that almost all of the git-svn runtime is being
spent in DynaLoader (via SVN::Base::import) which I guess is slow in a
virtualized windows environment. For example:

$ time perl /libexec/git-core/git-svn rebase
Current branch master is up to date.

real 2m56.750s
user 0m3.129s
sys 2m39.232s

I've been able to make significant (an order of magnitude)
improvements to it's performance by delaying SVN::Base::import from
running until it's actually needed. After making this change:

$ time perl /libexec/git-core/git-svn rebase
Current branch master is up to date.

real 0m33.407s
user 0m1.409s
sys 0m23.054s

git svn rebase -n goes from 3m7.046s to 0m10.312s.

Would love to get some feedback/thoughts etc...

j.

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--- git-svn.orig	Wed Jul 29 22:55:26 2009
+++ git-svn	Fri Dec  4 13:38:52 2009
@@ -27,11 +27,13 @@
 $| = 1; # unbuffer STDOUT
 
 sub fatal (@) { print STDERR "@_\n"; exit 1 }
-require SVN::Core; # use()-ing this causes segfaults for me... *shrug*
-require SVN::Ra;
-require SVN::Delta;
-if ($SVN::Core::VERSION lt '1.1.0') {
-	fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)";
+sub _req_svn {
+	require SVN::Core; # use()-ing this causes segfaults for me... *shrug*
+	require SVN::Ra;
+	require SVN::Delta;
+	if ($SVN::Core::VERSION lt '1.1.0') {
+		fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)";
+	}
 }
 my $can_compress = eval { require Compress::Zlib; 1};
 push @Git::SVN::Ra::ISA, 'SVN::Ra';
@@ -4379,6 +4381,8 @@
 	my ($class, $url) = @_;
 	$url =~ s!/+$!!;
 	return $RA if ($RA && $RA->{url} eq $url);
+
+	::_req_svn();
 
 	SVN::_Core::svn_config_ensure($config_dir, undef);
 	my ($baton, $callbacks) = SVN::Core::auth_open_helper(_auth_providers);

Re: [patch] git svn slowness on win32

[Johannes Schindelin]

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Hi,

On Tue, 16 Feb 2010, josh robb wrote:

> I'm using git svn (1.6.4.msysgit.0) within a WindowsXP VM running
> under VMWare fusion on OSX 10.5. For me (and at least one other person
> I know) git svn has been unbearably slow.
> 
> My profiling shows that almost all of the git-svn runtime is being
> spent in DynaLoader (via SVN::Base::import) which I guess is slow in a
> virtualized windows environment. For example:
> 
> $ time perl /libexec/git-core/git-svn rebase
> Current branch master is up to date.
> 
> real 2m56.750s
> user 0m3.129s
> sys 2m39.232s
> 
> I've been able to make significant (an order of magnitude)
> improvements to it's performance by delaying SVN::Base::import from
> running until it's actually needed. After making this change:
> 
> $ time perl /libexec/git-core/git-svn rebase
> Current branch master is up to date.
> 
> real 0m33.407s
> user 0m1.409s
> sys 0m23.054s
> 
> git svn rebase -n goes from 3m7.046s to 0m10.312s.
> 
> Would love to get some feedback/thoughts etc...

How about the following commit message (trying to follow 
http://repo.or.cz/w/git.git?a=blob;f=Documentation/SubmittingPatches;hb=HEAD):

-- snip --
git svn: delay importing SVN::Base until it is needed

Importing functions from a .dll into Git for Windows' perl is pretty slow,
so let's avoid importing if it is not necessary.

[... timing statistics here...]

Signed-off-by: Josh Robb <josh_robb@fastmail.fm>
-- snap --

Hmm?

Ciao,
Dscho

Re: [patch] git svn slowness on win32

[Eric Wong]

Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
> Hi,
> 
> On Tue, 16 Feb 2010, josh robb wrote:
> 
> > I'm using git svn (1.6.4.msysgit.0) within a WindowsXP VM running
> > under VMWare fusion on OSX 10.5. For me (and at least one other person
> > I know) git svn has been unbearably slow.
> > 
> > My profiling shows that almost all of the git-svn runtime is being
> > spent in DynaLoader (via SVN::Base::import) which I guess is slow in a
> > virtualized windows environment. For example:
> > 
> > $ time perl /libexec/git-core/git-svn rebase
> > Current branch master is up to date.
> > 
> > real 2m56.750s
> > user 0m3.129s
> > sys 2m39.232s
> > 
> > I've been able to make significant (an order of magnitude)
> > improvements to it's performance by delaying SVN::Base::import from
> > running until it's actually needed. After making this change:
> > 
> > $ time perl /libexec/git-core/git-svn rebase
> > Current branch master is up to date.
> > 
> > real 0m33.407s
> > user 0m1.409s
> > sys 0m23.054s
> > 
> > git svn rebase -n goes from 3m7.046s to 0m10.312s.
> > 
> > Would love to get some feedback/thoughts etc...
> 
> How about the following commit message (trying to follow 
> http://repo.or.cz/w/git.git?a=blob;f=Documentation/SubmittingPatches;hb=HEAD):
> 
> -- snip --
> git svn: delay importing SVN::Base until it is needed
> 
> Importing functions from a .dll into Git for Windows' perl is pretty slow,
> so let's avoid importing if it is not necessary.
> 
> [... timing statistics here...]
> 
> Signed-off-by: Josh Robb <josh_robb@fastmail.fm>
> -- snap --

Hi Josh,

Your patch was missing a call to ::req_svn() in cmd_branch(), but
otherwise it appears fine and passes all tests.

Can you write a proper commit message + patch so we can apply
it cleanly as Johannes suggested?  Thanks!

(full diff below)

diff --git a/git-svn.perl b/git-svn.perl
index 473a0b9..224c29f 100755
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -36,11 +36,13 @@ $ENV{TZ} = 'UTC';
 $| = 1; # unbuffer STDOUT
 
 sub fatal (@) { print STDERR "@_\n"; exit 1 }
-require SVN::Core; # use()-ing this causes segfaults for me... *shrug*
-require SVN::Ra;
-require SVN::Delta;
-if ($SVN::Core::VERSION lt '1.1.0') {
-	fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)";
+sub _req_svn {
+	require SVN::Core; # use()-ing this causes segfaults for me... *shrug*
+	require SVN::Ra;
+	require SVN::Delta;
+	if ($SVN::Core::VERSION lt '1.1.0') {
+		fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)";
+	}
 }
 my $can_compress = eval { require Compress::Zlib; 1};
 push @Git::SVN::Ra::ISA, 'SVN::Ra';
@@ -730,6 +732,7 @@ sub cmd_branch {
 		$src=~s/^http:/https:/;
 	}
 
+	::_req_svn();
 	my $ctx = SVN::Client->new(
 		auth    => Git::SVN::Ra::_auth_providers(),
 		log_msg => sub {
@@ -4859,6 +4862,8 @@ sub new {
 	$url =~ s!/+$!!;
 	return $RA if ($RA && $RA->{url} eq $url);
 
+	::_req_svn();
+
 	SVN::_Core::svn_config_ensure($config_dir, undef);
 	my ($baton, $callbacks) = SVN::Core::auth_open_helper(_auth_providers);
 	my $config = SVN::Core::config_get_config($config_dir);

-- 
Eric Wong