[jira] [Commented] (JCR-2927) Shutdown of JCR with o.a.j.c.persistence.pool.DerbyPersistenceManager leaves embedded Derby running

["Thomas Mueller (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JCR-2927?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13010029#comment-13010029 ] 

Thomas Mueller commented on JCR-2927:
-------------------------------------

I would rather not use "jdbc:derby:;shutdown=true" by default as it will close *all* Derby databases. What happens if multiple repositories are open, or if another application has a Derby database open at the same time? As far as I understand, this would also close those connections.

One option is to use another database that doesn't have such problems. One example is the H2 database - http://h2database.com - disclaimer: I'm one of the H2 committers. I think HSQLDB should be fine as well (not sure).

Another option is to call DriverManager.getConnection("jdbc:derby:;shutdown=true") yourself of course.

> Shutdown of JCR with o.a.j.c.persistence.pool.DerbyPersistenceManager leaves embedded Derby running
> ---------------------------------------------------------------------------------------------------
>
>                 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
>              Labels: cleanup, leaks
>
> 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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