tomcat-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
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 16:01:05 GMT
> From: Christopher Schultz [mailto:chris@christopherschultz.net] 
> Subject: Re: Follow-up: Possible false-postive with JreMemoryLeakPreventionListener 
> and Tomcat's JDBC Pool and OracleTimeoutPollingThread

> Thanks for the pedantry: I was in fact ignoring the difference between
> the system and boot ClassLoaders. However, the primordial ClassLoader
> does in fact exist, and does in fact load classes, and is not called
> the "boot" ClassLoader.

What you're calling the primordial class loader _is_ the boot class loader, identified by
a null reference.  (The use of "primordial" in the page you referred to is unusual; it's known
as the boot or bootstrap class loader in almost all other documentation.)  It's responsible
for more than just the java.* packages, since it also loads all the com.sun.*, sun.*, and
other JVM-vendor supplied classes.  I ignored the extensions class loader, since it's rarely
used and was not pertinent to the topic.

> the system class loader is represented by an "ExtClassLoader".  On top 
> of that is an AppClassLoader.

What you're looking at is JVM-internal classes (hence the $ in the names), that just happen
to be the ones chosen in current versions of the JVM.  The name is an implementation detail;
the internal class mechanism is used to handle privilege issues.  The internal names should
not be construed as descriptive of the class loader hierarchy.

> On top of that is an AppClassLoader.

Only for programs that supply their own, such as Tomcat.  My comments concerned the JVM itself,
not Tomcat.

> DriverManager's ClassLoader is in fact null, the primordial class loader.

Unless one configures a replacement DriverManager (I think there's a system property for that,
but I'm not sure).

 - Chuck


THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus
for use only by the intended recipient. If you received this in error, please contact the
sender and delete the e-mail and its attachments from all computers.


---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org


Mime
View raw message