Bug 406346

Description Brian Vosburgh 2013-04-23 12:23:49 EDT

Created attachment 230034 [details]
stack trace for IllegalArgumentException

During workspace start-up we (Dali) initialize a set of "JPA projects". That is, we build a JPA project for every project in the workspace with a JPA facet (facets are used by the WTP Faceted Project nature). Until recently, we would lock the workspace root while we built our JPA projects (via a scheduling rule for the initialization job). This would cause a performance/usability problem if any project was particularly large - the user would not be able to modify and save any files in unrelated projects until the Dali initialization job was finished (see bug 379755).

In an attempt to reduce the impact of Dali's initialization, we changed our code to schedule multiple jobs, one for each project in the workspace and each locking only that project while building the corresponding JPA project. In the course of building a JPA project, we ask the corresponding Java project whether a particular resource is on the Java project's classpath (IJavaProject.isOnClasspath(IResource)). Sometimes, although not often, this can result in an IllegalArgumentException

java.lang.IllegalArgumentException: Attempted to beginRule: P/Foo, does not match outer scope rule: P/Bar

because the method JavaProject.isOnClasspath(IResource) can trigger a workspace-wide initialization (JavaModelManager.initializeAllContainers(...)). This will trigger a Project.touch(...) on every project in the workspace and each touch will try to acquire a lock on the corresponding project. This is not allowed within the scope of the Dali lock of some other, unrelated project. See the attached stack trace.

My questions:
Isn't it a bit unexpected that the method IJavaProject.isOnClasspath(IResource)can require a lock on every project in the workspace? Is that the expected behavior? If so, the method needs a bit better documentation. Also, if this is expected behavior, how can we work around it, presumably by triggering the mass initialization outside our initialization jobs?