Shutdown of JCR with o.a.j.c.persistence.pool.DerbyPersistenceManager leaves
embedded Derby running
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Key: JCR-2927
URL: https://issues.apache.org/jira/browse/JCR-2927
Project: Jackrabbit Content Repository
Issue Type: Bug
Components: jackrabbit-core
Affects Versions: 2.2.4
Environment: JDK 1.6
Reporter: Brian Topping
Using org.apache.jackrabbit.core.persistence.pool.DerbyPersistenceManager will
cause embedded Derby to be started properly but not completely shut down. This
is most easily seen looking at a thread dump after the repositories have been
shut down, there will be a thread created by Derby called "derby.antiGC" still
running. This is critical under a webserver like Tomcat (all versions
including 7) to not leak a lot of memory when a context is reloaded.
The information I found to solve the issue is in
http://objectmix.com/apache/647660-derby-causes-permgen-leaks-tomcat.html#post2290996.
At shutdown, org.apache.jackrabbit.core.util.db.DerbyConnectionHelper has it's
shutDown() method called, but that only shuts down individual workspaces, for
instance with a URL of "jdbc:derby:leakDB;shutdown=true". The embedded
database is still left running.
To shutdown the database service itself, "jdbc:derby:;shutdown=true" must be
used (note the missing database).
I'm not at all confident I understand the shutdown process well enough to craft
a patch that would be worth evaluation. On the other hand, I have hacked
together a skanky proof-of-concept that caches the DataSource for a known
workspace before repository shutdown, then closes the database itself with the
noted URL. It works, and in turn all the threads and memory with a reference
of the webapp classloader are released.
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