Daniel Johnson created MNG-6398:
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Summary: Multithread Build Hangs Execution with sonar:sonar goal
when Aggregator POM references a Child Module as its Parent
Key: MNG-6398
URL: https://issues.apache.org/jira/browse/MNG-6398
Project: Maven
Issue Type: Bug
Components: core
Affects Versions: 3.5.3, 3.3.9, 3.2.5, 3.0.5
Environment: Apache Maven 3.5.3
(3383c37e1f9e9b3bc3df5050c29c8aff9f295297; 2018-02-24T11:49:05-08:00)
Maven home: /Users/danijoh2/Work/maven-3.5.3
Java version: 1.8.0_152, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.8.0_152.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.13.4", arch: "x86_64", family: "mac"
Reporter: Daniel Johnson
Attachments: maven-hanging-stack.txt,
maven-multithread-hanging-sample.zip
h1. Problem Statement
I have an Aggregator POM whose Parent POM is also one of its child Modules.
When I run a multi-thread Maven build with normal goals, such as 'clean
install' it works as expected; The Parent module builds first followed by the
Aggregator.
However when running '{{mvn sonar:sonar -T 2'}} the build hangs indefinitely
(from {{org.sonarsource.scanner.maven:sonar-maven-plugin:3.4.0.905}}).
h1. Sample Project
Attached.
h3. Layout
{{/pom.xml}}
{{/parent/pom.xml}}
h1. Reproducing the Issue
A normal multi-threaded build should work as expected: {{mvn clean install -T
2}}
But when running sonar goal, it hangs indefinitely: {{mvn sonar:sonar -T 2}}
(This can also be reproduced with {{mvn clean install sonar:sonar -T 2}}, in
which case it hangs immediately after building and installing both projects)
{{DANIJOH2-M-C5DB:deadlock-sample danijoh2$ mvn sonar:sonar -T 2}}
{{[INFO] Scanning for projects...}}
{{[INFO]
------------------------------------------------------------------------}}
{{[INFO] Reactor Build Order:}}
{{[INFO] }}
{{[INFO] parent [pom]}}
{{[INFO] aggregator [pom]}}
{{[INFO] }}
{{[INFO] Using the MultiThreadedBuilder implementation with a thread count of
2}}
{{<process is now hung>}}
Running the same build with a single thread works fine: {{mvn sonar:sonar}}
h2. Stack Trace of Hanging Maven Process
Attached.
h2. Summary
I saw the same behavior with Maven 3.0.5, 3.2.3, and 3.3.9, as well with
sonar-maven-plugin 3.0 and 3.3.0.603 with the same results. From the stack
trace, it seems Maven itself is hung (not deadlocked though), and while it may
be caused by the Sonar plugin, it seems the fix likely needs to come from Maven.
If I make the aggregator itself the parent (and get rid of the parent module
entirely) then it works fine. The problem with this approach, is in our project
we are also creating aggregated site reports for our project, which if I recall
correctly when I tried this last time, the aggregated reports were not always
working as expected when the aggregator POM builds before its modules.
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