[fedora-java] Getting rid of maven2-depmap.xml

[Alexander Kurtakov]

On 11:17:23 PM Saturday, June 11, 2011 Mat Booth wrote:
> On 10 June 2011 12:06, Alexander Kurtakov <akurtako at redhat.com> wrote:
> > On 01:58:33 PM Friday, June 10, 2011 Alexander Kurtakov wrote:
> >> On 01:01:39 PM Friday, June 10, 2011 Stanislav Ochotnicky wrote:
> >> > This is just an update on progress on migrating from maven2 to maven
> >> > package.
> >> > 
> >> > I just committed changes to maven package that will do a few things:
> >> >  * direct processing of fragment files generated by %add*_maven_depmap
> >> > 
> >> >    macros
> >> > 
> >> >  * being able to process fragments in /usr/share/maven-fragments
> >> >  * being able to resolve pom files in /usr/share/maven-poms
> >> > 
> >> > This will mean several things once the whole puzzle is created:
> >> >  * No need for %update_maven_depmap macro in %post and %postun
> >> >  * With it - no need for Require(post): jpackage-utils
> >> >  * No more rpmlint warnings about non-conf file in /etc
> >> >  * Sane place for pom files :-)
> >> >  * Simpler packaging (IMO)
> >> >  * Later on simpler patches to maven once we remove compat code.
> >> > 
> >> > For now we are backward compatible, so maven still reads from
> >> > /etc/maven/fragments and old _mavenpomdir.
> >> > 
> >> > Obviously there is certain performance penalty for processing few
> >> > hundred small files instead of one big file. However this performance
> >> > hit is rather small and only affects mvn-local and mvn-rpmbuild
> >> > so it won't affect users.
> >> > 
> >> > Worst case scenario, I'd rather move regenerating of depmaps into
> >> > maven shell script (comparing last change of depmap.xml with last
> >> > modification of fragments and all that...).
> >> > 
> >> > Right now no packaging modifications are necessary, since we don't
> >> > want to break maven2 just yet :-)
> >> > 
> >> > Next up: jpackage-utils and generation of maven2-depmap.xml even from
> >> > /usr/share/maven-fragments (for maven2 compat).
> >> > 
> >> > 
> >> > See https://fedoraproject.org/wiki/Migration_from_maven2 for more
> >> > details and plan.
> >> 
> >> Everything that simplifies packaging and doesn't degrade performance is
> >> an absolute win :).
> >> I'm already impressed with the speed improvements with our packaged
> >> version of maven 3.x (it's few times! faster not few percents) so few
> >> percents performance hit won't be noticed from people moving from
> >> maven2 to maven 3.x.
> > 
> > Just to put some details. All executions are on my laptop 3rd attempt so
> > all the caches are hot :)
> > 
> > qdox package build with maven2:
> > real    1m51.801s
> > user    1m36.492s
> > sys     0m9.199s
> > 
> > qdox package build with maven3:
> > real    0m41.633s
> > user    0m49.766s
> > sys     0m5.210s
> > 
> > 
> > Isn't it impressive? :) Let's say ~3 times faster for.
> 
> Nice, I didn't expect such massive improvements there. :-) Do you
> happen to know what the bottleneck was in maven2? Where was it
> spending all of its time?

Yup, 
Stanislav wrote a new resolver that uses jars from /usr/share while maven2 was 
coping them to local repo. :) This change surely caused the biggest 
improvement.

Alex