[MNG-5312] MavenProject.getParent intolerably slow when import scope used heavily

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.4
• Fix Version/s: 3.1.0-alpha-1
• Component/s: Embedding
• Environment: JDK 7, Ubuntu
• Flags: Patch
• Assignee: Jason van Zyl
• Reporter: Jesse N. Glick
• Created: 17/Jul/12 15:27
• Updated: 08/Jun/16 14:12
• Resolved: 18/Jul/12 07:41

Description

For projects which make heavy use of <scope>import</scope> including in parent POMs, calling MavenProject.getParent (thus DefaultProjectBuilder.build(Artifact, ...)) can be intolerably slow - taking many minutes - even when loading the project (or its parent) via DefaultProjectBuilder.build(List<File>, ...) takes less than a second.

The discrepancy seems to be due to the fact that ReactorModelCache is crucial for the performance of DefaultModelBuilder.importDependencyManagement, yet only one DefaultProjectBuilder.build overload defines a ModelCache. For resolution of parents from a single POM, no model cache is likely to be needed under normal circumstances, but if you are missing a cache when import scope dependencies are processed for <dependencyManagement>, the builder takes exponential time to find these imports.

I do not have a minimal test case for this yet as the known test case involves a large and complex proprietary source base. Patch (baseline is 3.0.4) successfully tested against these sources and shown to reduce getParent times by orders of magnitude.

https://issues.jenkins-ci.org/browse/JENKINS-11362 is the downstream issue describing symptoms.

Issue Links

• breaks: MNG-6030 ReactorModelCache do not used effectively after maven version 3.0.5 which cause a large memory footprint
• is related to: MNG-5314 DefaultModelValidator misuses String.matches
• is related to: MNG-5313 Unnecessary DefaultModelBuilder.build overload