"Artifact is not fully assembled" error with maven-invoker-plugin in parallel build - maven

Question

According to the docs, maven-invoker-plugin is "thread-safe and supports parallel builds." However, when I build by multi-module project with -T 1C, I get an error like the following:
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-invoker-plugin:1.10:install (integration-test) on project my-archetype: Failed to install project dependencies: MavenProject: com.tavianator:my-archetype:1.6-SNAPSHOT # /home/tavianator/code/Project/my-archetype/pom.xml: Failed to install project artifacts: MavenProject: com.tavianator:my-project:1.6-SNAPSHOT # /home/tavianator/code/Project/my-project/pom.xml: Failed to install artifact: com.tavianator:my-project:jar:1.6-SNAPSHOT: Artifact is not fully assembled: /home/tavianator/code/Project/my-project/target/classes -> [Help 1]
The project layout is like this:
Root
|--Project 1
|--Project 2
|--Archetype (depends on Project 1, scope=test)
The archetype integration tests use the maven-invoker-plugin to install the relevant dependencies (Root and Project 1) to a local repository, then runs the normal archetype integration tests. In parallel builds, Archetype and Project 2 run at the same time. When the maven-invoker-plugin runs, it tries to install Project 2 to the local repo, but Project 2 isn't built yet, hence the error.
But since Project 2 isn't even needed for the tests, I should be able to work around the problem by explicitly installing only the needed dependencies. I don't see how to get the invoker plugin to do that, but is there another plugin I can use?
I reported the maven-invoker-plugin bug here. I have an example project that demonstrates the error here.

Answer 1

I ran into this problem as well, in addition to other problems with the setup suggested in Fast Build Configuration (such as some artifacts being downloaded by the invoked project in every run), and implemented my own solution. Instead of the invoker:install goal, you would use the following:
<plugin>
<groupId>com.github.veithen.invoker</groupId>
<artifactId>resolver-proxy-maven-plugin</artifactId>
<version>0.1</version>
<executions>
<execution>
<goals>
<goal>start</goal>
<goal>stop</goal>
</goals>
</execution>
</executions>
</plugin>
Note that there is no need to explicitly configure settings.xml or a dedicated local repository. This is done automatically.
Currently the code in the plugin is experimental. If it turns out to be robust enough, I will submit a patch integrating it into maven-invoker-plugin. More information here.