[MNG-7536] Mojo execution locking in Maven 3.8.5 deadlocks my plugin

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Information Provided
• Affects Version/s: 3.8.5, 3.8.6
• Assignee: Guillaume Nodet
• Reporter: David Elliott
• Created: 04/Sep/22 08:13
• Updated: 05/Jan/23 07:05
• Resolved: 05/Jan/23 07:05

Description

I have an existing mojo which stopped working in Maven 3.8.5 but had been working for years.  It looks like MNG-7156 is the cause.

This mojo looks through its dependencies for other reactor projects, then looks at those projects for any plugin executions with a special phase name.  For all found executions, it executes them in a thread pool as part of some other processing it is doing.

My plugin is proprietary and I am unable to share it, but I am able to share a much smaller example illustrating the problem.

Being example code, it just spawns a thread to run the mojo executions and attempts to join the thread.  In the real code all executions for a given project will run sequentially on one thread, but each project's work will be scheduled concurrently on a thread pool.

I didn't feel it was necessary to use a thread pool and schedule more than one project's executions for this example.  The deadlock will occur simply by running any mojo at all on a secondary thread while the calling thread is running a mojo waiting for that secondary thread to complete.

Issue Links

• is caused by: MNG-7156 Parallel build can cause issues between clean and forked goals