[jira] [Commented] (MNG-6311) Maven intolerably slow when import scope used heavily in large project

["Thomas Nikolay (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MNG-6311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16602261#comment-16602261 ] 

Thomas Nikolay commented on MNG-6311:
-------------------------------------

[~khmarbaise] you can this not test on the master because it is on a fix branch fix/MNG-6311. But I checked it out from there and build of maven.

After that I run a smoke test on the affected project and it was faster as before 3.3.9 :)

> 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
>            Priority: Major
>              Labels: performance
>         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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