问题
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
回答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
回答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.
回答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:
回答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.
回答5:
set eclipse_dir=D:\eclipse\release
mkdir %eclipse_dir%\disabled
mkdir %eclipse_dir%\disabled\features
mkdir %eclipse_dir%\disabled\plugins
move %eclipse_dir%\plugins\org.eclipse.jpt.* disabled\plugins
for /f %%i in ('dir features\org.eclipse.jpt.*" /ad /b') do (
move features\%%i" "%eclipse_dir%\disabled\features\%%i"
)
回答6:
I had the same issue I had the same issue in eclipse 4.5.2 (mars 2). I've tried almost every answer from stackoverflow, tuned my eclipse settings (I thought maybe its a performance issue).
Problem stops after disabling JPA in Project Facets in every Project properties.
After this change Eclipse keeps yelling about JPA Event Handler but it doesn't take ages to finish save or clean, so it looks like its disabled (before changing this it took something about 10 minutes to finish, now its matter of seconds)
Hope that help someone to fix this problem.
来源：https://stackoverflow.com/questions/11631371/why-is-eclipse-juno-4-2-running-jpa-java-change-event-handler-processes