[JCR-2378] Avoid exceptions thrown in finalize handler of RepositoryImpl constructor

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0-alpha11
• Fix Version/s: 2.0-beta3
• Component/s: jackrabbit-core
• Assignee: Alexander Klimetschek
• Reporter: Alexander Klimetschek
• Created: 02/Nov/09 14:25
• Updated: 11/Jan/10 14:16
• Resolved: 02/Nov/09 16:02

Description

If an exception happens during initialization of the repository, it might be overlayed by an exception thrown in the finalize handler of the RepositoryImpl constructor (see line 382 ff in [1]). The latter exception wins and the original exception is lost (if you don't have a log). This makes it hard to figure out the real problem.

This problem is actually a bit self-enforcing: if something goes wrong during startup, the code in the shutdown() method that is called is actually very prone to fail as it might not expect such a broken-startup state. In my case the overlaying NPE happened in ObservationManagerImpl.getRegisteredEventListeners, where this.dispatcher was unexpectedly null [2].

I think both places should be fixed (NPE guard in ObservationManagerImpl constructor for "dispatcher") and a try/catch block in the finalizer, just logging the exception:

} finally {
if (!succeeded) {
try

{ // repository startup failed, clean up... shutdown(); }

catch (Throwable t)

{ // shutdown() likely to fail now, as startup was broken... log.error("In addition to startup fail, another problem occurred while shutting down the repository again.", e); }

}
}

[1] http://svn.apache.org/viewvc/jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/RepositoryImpl.java?view=markup

[2] Overlaying exception's stacktrace:
Caused by: java.lang.NullPointerException
at org.apache.jackrabbit.core.observation.ObservationManagerImpl.getRegisteredEventListeners(ObservationManagerImpl.java:143)
at org.apache.jackrabbit.core.SessionImpl.removeRegisteredEventListeners(SessionImpl.java:1190)
at org.apache.jackrabbit.core.SessionImpl.logout(SessionImpl.java:1215)
at org.apache.jackrabbit.core.RepositoryImpl$WorkspaceInfo.doDispose(RepositoryImpl.java:2153)
at com.day.crx.core.CRXRepositoryImpl$CRXWorkspaceInfo.doDispose(CRXRepositoryImpl.java:1095)
at org.apache.jackrabbit.core.RepositoryImpl$WorkspaceInfo.dispose(RepositoryImpl.java:2108)
at org.apache.jackrabbit.core.RepositoryImpl.doShutdown(RepositoryImpl.java:1146)
at com.day.crx.core.CRXRepositoryImpl.doShutdown(CRXRepositoryImpl.java:845)
at org.apache.jackrabbit.core.RepositoryImpl.shutdown(RepositoryImpl.java:1098)
at org.apache.jackrabbit.core.RepositoryImpl.<init>(RepositoryImpl.java:387)
at com.day.crx.core.CRXRepositoryImpl.<init>(CRXRepositoryImpl.java:201)
at com.day.crx.core.CRXRepositoryImpl.create(CRXRepositoryImpl.java:190)
... 28 more

Issue Links

• is related to: JCR-2380 NPE in ObservationManagerImpl.getRegisteredEventListeners() during shutdown after broken startup