NonStop Server for Java 7.0 Programmer's Reference

NOTE: The -tclient option is not valid with NSJ7.
-tserver
Runs the application in the Java HotSpot server VM.
NOTE: The -tserver is the default option for NSJ7. Hence, specifying -tserver
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 7.0 Tools Reference Pages.
Garbage collection (GC)
This section discusses the following implementation-specific topics about garbage collection for
NSJ7:
• “General information on garbage collection” (page 51)
• “Heap layout” (page 51)
• “Managing generation size” (page 52)
• “Implementation of garbage collector types” (page 53)
General information on garbage collection
In general, the various GC algorithms, and modeling in NSJ7 are same as those implemented by
Oracle in their JVM. Accordingly, you must refer to the Java web site for details about garbage
collection. However, some of the information is not applicable to NSJ7. For more relevant
information, see the following links on Java web site:
• Java SE 7 HotSpot Virtual Machine Garbage Collection Tuning
• 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.
Although, this paper was written for JDK1.4.1, it contains information related to tuning
application behavior using data in verbose GC logs, which is applicable to JDK 7.0.
Heap layout
In NSJ7, the memory is managed in generations (or memory pools) based on objects at different
ages for Java objects. Figure 2 (page 52) illustrates the heap layout for generations.
Garbage collection (GC) 51