Java Performance Tuning – Introduction
Java Performance Tuning
The Java programming language is an object oriented and includes automatic garbage collection.
Garbage collection is the process of reclaiming memory taken up by unreferenced objects.
The following sections will try to resume some of the concepts from this document and their impact on Application Server performance.
Memory Management, Java and Impact on Application Servers
The task of memory management that was always challenging with compiled object‐oriented languages such as C++.
On the other hand, Java is an interpretive language that takes this memory management
out of the hands of developers and gives it directly to the virtual machine where the code will be run.
This means that for best performance and stability, it is critical that the Java parameters for the virtual machine be understood and managed by the Application Server deployment team.
This section will describe the various parts of the Java heap and then list some useful parameters and tuning tips for ensuring correct runtime stability and performance of Application Servers.
Java Virtual Machines
The Java specification as to what is “standard” for a given release is written and maintained by the Java Soft division of Sun Microsystems.
This specification is then delivered to other JVM providers (IBM, HP, etc). JavaSoft provides the standard implementation on Windows, Solaris, and LINUX.
Other platforms are required to deliver the code functionality but their JVM options can be different.
Java options that are preceded with “‐X” or “‐XX” are typically platform‐specific.
That being said, many options are used on all platforms.
One must read in detail the README notes from the various releases on various platforms to be kept up‐to‐date with the variations.
This guide will mention the most critical ones and distinguish between those which are implemented on most platforms and those which are platform‐specific.
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