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https://issues.apache.org/jira/browse/MNG-6030?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15307579#comment-15307579
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Andriy edited comment on MNG-6030 at 5/31/16 11:20 AM:
-------------------------------------------------------
What i found while my investigation:
I locally added logging in the cache class to calculate cache miss and found
the cache in not used for parent pom.
In our project I made local change for sharing the cache between modules and it
cause smaller footprint.(the same as was in maven 3.0.5)
according to the DefaultProjectBuilder$InterimResult . it contains
ModelBuildingResultinside it
{code}
ModelBuildingRequest request = getModelBuildingRequest( config );
....
ModelBuildingResult result = modelBuilder.build( request );
...
InterimResult interimResult = new InterimResult( pomFile, request,
result, listener, isRoot );
{code}
and each ModelBuildingRequest has separate instance of the cache inside it
{code}
request.setModelCache( new ReactorModelCache() );
{code}
so now we has as many InterimResult as we has modules and because of the not
reused caches also so many parsed parent poms in each cache.
Also we has a large cache miss value while build.
reusing ReactorModelCache will cause smaller footprint of the interimResult
and smaller cache miss value for the cache too.
was (Author: sandriy):
What i found while my investigation:
I locally added logging in the cache class to calculate cache miss and found
the cache in not used for parent pom.
In our project I made local change for sharing the cache between modules and it
cause smaller footprint.(the same as was in maven 3.0.5)
according to the DefaultProjectBuilder$InterimResult . it contains
ModelBuildingResultinside it
{code}
ModelBuildingRequest request = getModelBuildingRequest( config );
....
ModelBuildingResult result = modelBuilder.build( request );
...
InterimResult interimResult = new InterimResult( pomFile, request,
result, listener, isRoot );
{code}
and each ModelBuildingRequest has separate instance of the cache inside it
{code}
request.setModelCache( new ReactorModelCache() );
{code}
so now we has as many InterimResult as we has modules and because of the not
reused caches also so many parsed parent poms in each cache.
Also we has a large cache miss value while build.
reusing ReactorModelCache will cause smaller footprint of the interimResult
and smaller cache miss result.
> ReactorModelCache do not used effectively after maven version 3.0.5 which
> cause a large memory footprint
> --------------------------------------------------------------------------------------------------------
>
> Key: MNG-6030
> URL: https://issues.apache.org/jira/browse/MNG-6030
> Project: Maven
> Issue Type: Improvement
> Components: Embedding
> Affects Versions: 3.1.1, 3.2.5, 3.3.3, 3.3.9
> Reporter: Andriy
> Labels: performance
> Attachments: screenshot-maven-3.0.5.png,
> screenshot-maven-3.3.9-details.png, screenshot-maven-3.3.9.png
>
>
> after version 3.0.5 we found a very big memory consumption with maven. needed
> for build memory grows from 1G to 5G
> According to current implementation there were change with commit
> https://git-wip-us.apache.org/repos/asf?p=maven.git;a=commit;h=e778ea67121f17232a7dced3fb4f0a205ffa64af
>
> https://issues.apache.org/jira/browse/MNG-5312
> {code}
> private ModelBuildingRequest getModelBuildingRequest( InternalConfig config )
> {
> @@ -256,7 +256,7 @@ public class DefaultProjectBuilder
> request.setUserProperties( configuration.getUserProperties() );
> request.setBuildStartTime( configuration.getBuildStartTime() );
> request.setModelResolver( resolver );
> - request.setModelCache( config.modelCache );
> + request.setModelCache( new ReactorModelCache() );
> return request;
> }
> {code}
> and as result new ReactorModelCache created for each ModelBuildingRequest
> which is created new to parse each pom.xml included in the build as module.
> so if there is a big projects with a lot of modules ModelBuildingRequest is
> created for each of them and parse result is not reused between modules. and
> if all this modules has the same parent pom it parsed each time and stored as
> many times as many ModelBuildingRequest was created. As parent pom often
> contains dependencies, dependencyManagement and common information for all
> modules it cause a larger memory footprint then was before. In version 3.0.5
> and earlier ReactorModelCache was single and was reused between
> ModelBuildingRequest.
> in our cause footprint grew from 1g to 5g.
> it will be better to reuse result of parsing pom files between
> ModelBuildingRequests.
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