NonStop Server for Java 6.0 Programmer's Reference

NOTE: The -tclient option is not valid with NonStop Server for Java 6.0.
-tserv
Runs the application in the Java HotSpot server VM.
NOTE: -tserv is the default option for NonStop Server for Java 6.0; therefore,
specifying -tserv is optional.
For more information about jdb and how to start a Java program so that jdb can attach to it, see
jdb in the NonStop Java 6.0 Tools Reference Pages.
Garbage Collection (GC)
This subsection discusses implementation-specific information about garbage collection for NonStop
Server for Java 6.0. The topics are:
• “General Information on Garbage Collection” (page 59)
• “Heap Layout” (page 59)
• “Managing Generation Size” (page 60)
• “Implementation of Garbage Collector Types” (page 61)
General Information on Garbage Collection
In general, garbage collectors, the various GC algorithms, and modeling in the NonStop Server
for Java 6.0 are the same as those implemented by Sun Microsystems in their JVM. Accordingly,
you should refer to the SunMicrosystems web site for details about garbage collection. But keep
in mind that some of the information is not applicable to NonStop Server for Java 6.0. Links to
pertinent information (but not all the information) on the SunMicrosystems web site are:
• Java SE 6 HotSpot Virtual Machine Garbage Collection Tuning
http://www.oracle.com/technetwork/java/javase/tech/index-jsp-136373.html)
• Turbo-charging the Java HotSpot Virtual Machine, v1.4.x to Improve the Performance and
Scalability of Application Servers by Alka Gupta and Michael Doyle
(http://java.sun.com/developer/technicalArticles/Programming/turbo/)
• Improving Java Application Performance and Scalability by Reducing Garbage Collection
Times and Sizing Memory Using JDK 1.4.1 by Nagendra Nagarajayya and J. Steven Mayer
( http://developers.sun.com/mobility/midp/articles/garbagecollection2/ )
Heap Layout
In NonStop Server for Java 6.0, the memory is managed in generations (or memory pools) based
on objects at different ages for Java objects. “Layout for Generations” (page 60) is illustrated and
described below.
Garbage Collection (GC) 59