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https://issues.apache.org/jira/browse/MNG-6311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16701504#comment-16701504
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Mickael Istria commented on MNG-6311:
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I've opened MNG-6530 to track resolution of this one on a pure technical side;
but again I think there is a process issue if those patches can get in even if
some concerns are raised way before the release. The project leads should
probably clarify some rules for applying patches and reverting them if they are
probably causing issues downstream and no test covers this.
> Maven intolerably slow when import scope used heavily in large project
> ----------------------------------------------------------------------
>
> Key: MNG-6311
> URL: https://issues.apache.org/jira/browse/MNG-6311
> Project: Maven
> Issue Type: Bug
> Components: core, Performance
> Affects Versions: 3.5.0, 3.5.2
> Reporter: David Churcher
> Assignee: Sylwester Lachiewicz
> Priority: Major
> Labels: performance
> Fix For: 3.6.0
>
> Attachments: Call-tree-–-All-threads-together.html,
> anon-hierarchy-maven-output.zip, modelcachefix.diff
>
>
> I have a build performance problem that is identical to MNG-5312, and has
> appeared since MNG-6030 in Maven v3.5.0 reversed the patch for MNG-5312,
> removing the ModelCache from some of the overloads for
> DefaultProjectBuilder.build.
> As in MNG-5312 the problem is in a large proprietary project. It uses up to 8
> levels of parent POMs, many of which use the import scope and have large
> dependency-management sections, and has hundreds of dependencies that also
> use the same parent POM hierarchy. Adding some logging shows that Maven does
> over 800,000 uncached reads of parent POM files, which takes about half an
> hour. With model caching this goes down to a few seconds.
> I've attached a patch that fixes this by using a class-level ModelCache in
> DefaultProjectBuilder. This does not suffer from the memory usage problems
> reported in MNG-6030.
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