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From "Caldarale, Charles R" <Chuck.Caldar...@unisys.com>
Subject RE: Follow-up: Possible false-postive with JreMemoryLeakPreventionListener and Tomcat's JDBC Pool and OracleTimeoutPollingThread
Date Thu, 23 May 2013 22:56:44 GMT
> From: Christopher Schultz [mailto:chris@christopherschultz.net] 
> Subject: Re: Follow-up: Possible false-postive with JreMemoryLeakPreventionListener
> and Tomcat's JDBC Pool and OracleTimeoutPollingThread

> While I haven't exactly implemented my own JVM or anything like that,

I have...

> I have often heard the boot class loader referred to as the primordial
> class loader.

Both the JVM and Java Language specs refer to it as the bootstrap class loader:
http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-5.html#jvms-5.3.1

The word "primordial" does not appear anywhere in the JVM spec, and only as a descriptive
term for the Object class in the language spec.

> So, at least in Oracle's JVM:

Also in any JVM serious about running Java programs.

> java.endorsed.dirs -> boot class loader     (null)

The boot[strap] class loader, as noted.

> java.ext.dirs      -> another class loader  (ExtClassLoader)

The extensions class loader, rarely used.

> java.class.path    -> a third class loader  (AppClassLoader)

The system class loader, officially (java.lang.ClassLoader.getSystemClassLoader()).

Interestingly enough, the above hierarchy does not appear in any spec I can find, although
you'd be hard pressed to find a JVM that doesn't implement it that way.

Using AppClassLoader as the internal name for the system class loader is unfortunate, since
it creates confusion with common usage and an actual Application Class Loader, as described
in this link:

http://docs.oracle.com/cd/E19501-01/819-3659/beadf/index.html

That one does seem like a bit of overkill...

 - Chuck


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