[KARAF-6697] karaf-maven-plugin verify goal leaks threads

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.2.7, 4.2.8
• Fix Version/s: 4.2.17, 4.4.3, 4.3.9
• Component/s: karaf
• Target Version/s: 4.2.17, 4.4.3, 4.3.9
• Assignee: Jean-Baptiste Onofré
• Reporter: Wouter Born
• Created: 28/Apr/20 14:30
• Updated: 26/Nov/22 06:03
• Resolved: 26/Nov/22 06:03

Description

We use the verify goal of the karaf-maven-plugin to verify 200+ features in our openHAB add-ons build (see pom.xml).

When monitoring the build using VisualVM the live thread counts keep increasing each time the verify goal is executed.

It increases to ~2000 threads after invoking the goal 200+ times:

 

 

When the plugin is removed from the build everything returns to normal (this was a full build with tests):

 

 

To reproduce it on our code:

1. git clone -b 2.5.x --single-branch [e-mail]:openhab/openhab-addons.git
2. cd openhab-addons
3. mvn clean install -DskipChecks -DskipTests
4. Monitor the live thread counts using a tool like VisualVM

When re-running the same build without Karaf feature validation, VisualVM will show that the live thread counts peak at 20 instead:

1. mvn clean install -DskipChecks -DskipTests -Dfeatures.verify.skip=true

I also tested the 4.2.8 version of the plugin but it was still leaking threads.