Fabian van der Veen created MNG-5960:
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Summary: MojoExecutor overriding resolved artifacts of
concurrently built MavenProject
Key: MNG-5960
URL: https://issues.apache.org/jira/browse/MNG-5960
Project: Maven
Issue Type: Bug
Affects Versions: 3.3.9, 3.4.0
Environment: Linux 4.2.0-23-generic #28-Ubuntu SMP Sun Dec 27 17:47:31
UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
(Ubuntu 15.10)
Maven 3.3.9/3.4.0-SNAPSHOT
Reporter: Fabian van der Veen
I have found an issue with respect to the {{MojoExecutor}} in {{maven-core}}
when building with multiple threads (e.g. {{-T1C}}).
I have created a small reproduction project here:
https://github.com/fvanderveen/maven-mojo-jojo (in the readme is some more
explanation of what I found to be the problem)
The reproduction, using the above code:
1. Clone this repository (`git clone
https://github.com/fvanderveen/maven-mojo-jojo.git`)
2. Make sure the clone works single-threaded: `mvn clean package`. (This should
succeed)
3. Clean the workspace (`mvn clean`)
4. Attempt multi-threaded compilation with at least 2 threads (`mvn package
-T2`)
Boiled down, it seems like the {{MojoExecutor#ensureDependenciesAreResolved}}
will cause an invocation to
{{LifecycleDependencyResolver#resolveProjectDependencies}} for _all_ projects
in the current {{MavenSession}} if it's configuring a plugin that defines
{{@Mojo(aggregator = true)}} and
{{DependencyContext#isResolutionRequiredForAggregatedProjects}} return true.
This resolving may, if triggered at an unfortunate time, override resolved
artifacts for projects that are being built concurrently.
In our case, a {{test-compile}} execution of the {{maven-compiler-plugin}} was
just configured (setting the resolved artifacts to the test-scope artifacts),
and right before its execution, the resolved artifacts got set back to the
compile-scope artifacts due to a aggregator plugin being configured at around
the same time.
Given the way the `ensureDependenciesAreResolved` is structured and what
aggregator plugins should do/depend on, I think it would make more sense to
_only_ invoke {{LifecycleDependencyResolver#resolveProjectDependencies}} for
the modules that are a (grand-)child of the current project.
I've created a maven extension (which can be placed in lib/ext) as a temporary
workaround using said change; which may be found here if any one else is having
the same problems:
https://github.com/fvanderveen/maven-non-destructive-mojo-executor
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