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https://issues.apache.org/jira/browse/MNG-7509?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Xiong Luyao updated MNG-7509:
-----------------------------
Description:
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. As below picture, there is over 3000 business domain
libraries, each library may rely on several other libraries among them. So the
library which didn’t rely on each other will be built first and the library
only relies on the built libraries will be built, until all the libraries have
been built. In this way, we use a parent pom to maintain the version of these
3000+ libraries version and make each library introduce it. So that it can keep
all the libraries are built from same base.
But 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 with 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!
was:
When maven try to resolve dependency relationship, it will create many objects
of dependency / artifact. Even the dependency/artifact content is totally same,
but just in different models. It cost huge memory if there is a big
dependencyManagement parent pom in each dependencies of the project.
Here is a real case. As below picture, there is over 3000 business domain
libraries, each library may rely on several other libraries among them. So the
library which didn’t rely on each other will be built first and the library
only relies on the built libraries will be built, until all the libraries have
been built. In this way, we use a parent pom to maintain the version of these
3000+ libraries version and make each library introduce it. So that it can keep
all the libraries are built from same base.
But 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 with 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!
> 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. As below picture, there is over 3000 business domain
> libraries, each library may rely on several other libraries among them. So
> the library which didn’t rely on each other will be built first and the
> library only relies on the built libraries will be built, until all the
> libraries have been built. In this way, we use a parent pom to maintain the
> version of these 3000+ libraries version and make each library introduce it.
> So that it can keep all the libraries are built from same base.
> But 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 with 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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