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https://issues.apache.org/jira/browse/MNG-7509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17564494#comment-17564494
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Xiong Luyao edited comment on MNG-7509 at 7/9/22 3:05 AM:
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Further more, if we add 'export MAVEN_OPTS="-Xms1g -Xmx1g”’ for this project
build to limit the max heap size. Before change, it throws OOM exception and
failed, but it works well after change.
!image-2022-07-09-10-29-46-216.png|width=340!
!image-2022-07-09-10-29-51-456.png|width=341!
was (Author: JIRAUSER292130):
Further more, if we add 'export MAVEN_OPTS="-Xms1g -Xmx1g”’ for this project
build to limit the max heap size. Before change, it will throw OOM exception,
but it works well after change.
!image-2022-07-09-10-29-46-216.png|width=340!
!image-2022-07-09-10-29-51-456.png|width=341!
> Huge memory cost when parent pom widely used in a big project for
> dependencyManagement
> --------------------------------------------------------------------------------------
>
> Key: MNG-7509
> URL: https://issues.apache.org/jira/browse/MNG-7509
> Project: Maven
> Issue Type: Improvement
> Components: Performance
> Reporter: Xiong Luyao
> Priority: Major
> Attachments: image-2022-07-09-09-37-53-823.png,
> image-2022-07-09-09-38-26-354.png, image-2022-07-09-10-27-12-668.png,
> image-2022-07-09-10-27-56-437.png, image-2022-07-09-10-28-05-706.png,
> image-2022-07-09-10-28-22-864.png, image-2022-07-09-10-28-35-341.png,
> image-2022-07-09-10-28-40-612.png, image-2022-07-09-10-29-04-045.png,
> image-2022-07-09-10-29-15-822.png, image-2022-07-09-10-29-21-991.png,
> image-2022-07-09-10-29-46-216.png, image-2022-07-09-10-29-51-456.png
>
>
> When maven try to resolve dependency relationship, it will create many
> instances of dependency / artifact, even the dependency/artifact content is
> totally same, but just in different pom models. It cost huge memory if there
> is a parent pom with dependencyManagement which managed a lot of
> dependencies, and this parent pom are implemented by many project libraries.
> (libraries_count * managedDependency_count) dependency instances will be
> created. For example, if there are 3000 libraries, and all the library
> introduce same parent pom which managed 3000 dependencies version. There will
> be 3000*3000 =9,000,000 dependency instances will be created. But most of
> them are same, in fact, we only need one instance for each dependency in
> parent pom (3000 dependency instances).
>
> Here is a real case in enterprise level project. We have about 3000 business
> domain libraries, there are dependency relationship between them. We need to
> build all libraries in one release to keep all the libraries in same release
> are based on same code. So we used a parent pom to manage all the version for
> a release, and introduced by those libraries. As below picture, when the
> release start, it will calculate and start with the library which doesn't
> depend on others, then start the library which dependency libraries are
> already built. Keep this process until all libraries are built.
> With current maven resolve logic, it costs huge memory in above ways to built
> libraries. And even the libraries have been released, if the project which
> contains a lot of above libraries, it also cost huge memory when building
> project.
>
> !image-2022-07-09-09-37-53-823.png|width=493,height=226!
>
> Here is a thread dump when building a real project which depends on about
> 1000 above libraries. The top 5 objects are all related to
> org.eclipse.aether.graph.Dependency.
> !image-2022-07-09-09-38-26-354.png|width=510,height=199!
>
>
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