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Posted to issues@maven.apache.org by "Bruno Medeiros (Jira)" <ji...@apache.org> on 2021/01/15 03:00:00 UTC

[jira] [Updated] (MSHADE-329) Concurrent writes of dependency-reduced-pom.xml adds same exclusion ad infinitum

     [ https://issues.apache.org/jira/browse/MSHADE-329?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bruno Medeiros updated MSHADE-329:
----------------------------------
    Attachment: mshade-329-stacktrace.txt

> Concurrent writes of dependency-reduced-pom.xml adds same exclusion ad infinitum
> --------------------------------------------------------------------------------
>
>                 Key: MSHADE-329
>                 URL: https://issues.apache.org/jira/browse/MSHADE-329
>             Project: Maven Shade Plugin
>          Issue Type: Bug
>    Affects Versions: 3.2.1
>            Reporter: Håkon Hallingstad
>            Priority: Major
>         Attachments: mshade-329-stacktrace.txt
>
>
> I have a multi-threaded {{mvn install}} that seems to halt but ends up using 200% CPU, in about 50% of the invocations. The {{mvn}} command used is:
> {panel}
> mvn -T1C -nsu -Dmaven.source.skip -Dmaven.javadoc.skip -Dmaven.test.skip install -rf :MODULE
> {panel}
> Using {{mvnDebug}} I have found out that there are 2 running Java threads, each writing {{dependency-reduced-pom.xml}} in two different modules {{A}} and {{B}}, respectively. These files seems to become several MB large, before they're deleted and then written again, and so forth.
> I have looked into one of the threads, and there is a {{rewriteDependencyReducedPomIfWeHaveReduction}} in ShadeMojo with a {{loopCounter}} with value 2735, that just keeps increasing. Presumably there is something like one dependency-reduced-pom.xml written per iteration.
> From the source code it seems this can only happen if https://github.com/apache/maven-shade-plugin/blob/master/src/main/java/org/apache/maven/plugins/shade/mojo/ShadeMojo.java#L1172 is hit at least that number of times, meaning the ShadeMojo adds that many exclusions, which seems to correspond to hamcrest-core:
> {noformat}
>  <dependencies>
>   <dependency>
>     <groupId>junit</groupId>
>     <artifactId>junit</artifactId>
>       <version>4.12</version>
>      <scope>test</scope>
>     <exclusions>
>       <exclusion>
>         <artifactId>hamcrest-core</artifactId>
>         <groupId>org.hamcrest</groupId>
>       </exclusion>
>       <exclusion>
>         <artifactId>hamcrest-core</artifactId>
>         <groupId>org.hamcrest</groupId>
>       </exclusion>
>      ...
> {noformat}
> {panel}
> grep hamcrest-core dependency-reduced-pom.xml | wc -l
>  2735
> {panel}
>  
> The same exclusion is added {{loopCounter}} times in {{updateExcludesInDeps}}.
> There is no problem running {{mvn}} in single-thread mode.



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