Why is Eclipse Juno 4.2 running "JPA Java Change Event Handler" processes?

Question

I have just upgraded to Eclipse Juno 4.2. I have a completely clean new workspace, but have imported projects that have previously been used in Eclipse 3.7 and therefore have some Eclipse metadata in them.

When moving to 4.2 I converted a project to use "Project Facets". The only Facet enabled is "Java".

However, I regularly get "JPA Java Change Event Handler (Waiting)" appearing in my progress view. I do have JPA annotated classes within the project, but I do not have the JPA facet enabled.

So...why am I getting these tasks being run by Eclipse?

Update: Have submitted bug to Eclipse and it is being looked at by the looks of it: https://bugs.eclipse.org/bugs/show_bug.cgi?id=386171

Answer 1

Unfortunately, the JPA java completion proposals extension point is incorrectly forcing o.e.jpt.jpa.core plug-in activation. Once our plug-in is activated we start listening for java events and facet events, whether JPA faceted or not. In Juno these background threads were converted to the Eclipse Jobs framework. In Helios you would not have seen them in the Progress View, but the same problem existed.

Thanks for entering a bug against Dali https://bugs.eclipse.org/bugs/show_bug.cgi?id=386171 for this problem.

Update: The bug has been fixed for Juno SR1, thanks to JDT Text for their quick turn around on this Dali bug!

Update 2: This problem is still occurring for other use cases. In Juno SR2 there are 3 bugs being worked on that will help resolve this issue. Some of these have further fixes that will need to go in Kepler. See bugs:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=397778

https://bugs.eclipse.org/bugs/show_bug.cgi?id=397606

https://bugs.eclipse.org/bugs/show_bug.cgi?id=386393

Answer 2

I've experienced this behavior whenever I disabled the JPA Validator in Window => Preferences => Validation. Enabling it for both Build and Manual made the crazy loop disappear.

Answer 3

I found (in Eclipse Neon where this still occurs) that removing all the groups in the JPA Validator worked well. Click on the box to the right of JPA Validator and remove all the included groups:

Answer 4

The drastic solution in my case was to uninstall "Dali JPA". That seemed to solve the issue for me.

Of course it is not the best solution. Try first to enable the validation as explained in NPE's anwser. Bug 386171 has people that report the same problem at May of 2015 so I must not be the only one.

I would be very happy to delete my answer if something better is found.