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https://issues.apache.org/jira/browse/MNG-5896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15071889#comment-15071889
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Harald Wellmann commented on MNG-5896:
--------------------------------------
With a [proposed
solution|https://github.com/hwellmann/aether-core/commit/cdab4c40094ccf621370647f83ecda54684066ce]
for this issue in {{aether-core}}, I tested dependency collection using a test
case similar to
{{org.apache.maven.repository.internal.RepositorySystemTest.testCollectDependencies()}}
for a number of artifacts, always starting with an empty local repository.
The tests were run with a current Maven 3.4.0-SNAPSHOT, with and without the
Aether patch applied:
Here are some results:
|||Artifact||unpatched||patched||
|org.apache.maven.plugins:maven-release-plugin:2.5.3|27.3 s|17.5 s|
|org.seleniumhq.selenium:selenium-java:2.48.2|15.8 s|7.6 s|
|org.apache.openejb:tomee-webapp:1.7.3|29.5 s|16.1 s|
The tests directly access Maven Central.
The effect of the patch is even more noticeable when Maven Central is mirrored
by a repository manager, where the added latency of the repository manager
acting as a proxy has a negative impact on downloading a lot of small files
like POMs.
> Download dependency POMs in parallel
> ------------------------------------
>
> Key: MNG-5896
> URL: https://issues.apache.org/jira/browse/MNG-5896
> Project: Maven
> Issue Type: Improvement
> Components: Dependencies
> Affects Versions: 3.3.3
> Reporter: Harald Wellmann
>
> h3. Background
> When building a project with dependencies not yet available in the local
> repository, I noticed that Maven 3.3.3 first downloads the dependency POMs
> _sequentially_ and then proceeds downloading the dependency JARs with up to 5
> threads _in parallel_.
> Due to this, when first building a project with a large number of
> dependencies, downloading a large number of small POMs may take a lot longer
> than downloading the much larger JARs, or even longer than building the
> project itself, especially when a repository manager is used which increases
> the download latency.
> h3. Enhancement
> Download POMs of (transitive) dependencies in parallel to significantly speed
> up initial builds of large projects.
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