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
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.