Why does WebSphere Application Server v5 use more memory than earlier releases?
 Technote (FAQ)
 
Question
This document explains why WebSphere Application Server Version 5 uses more disk space and more memory than previous versions of WebSphere.
 
Answer
WebSphere Application Server and the JDK have been enhanced to improve their usability and effectiveness; therefore, the disk space and memory required to run the WebSphere Application Server processes have increased.
Summary of Changes
While balancing usability, function and performance, these are the most significant changes that affect required disk space and memory:
  • Elimination of the Administrative Console as a Java thick client moved function into the server process.
  • Elimination of a database as the repository moved function into the server process. The WebSphere repository is now maintained in memory by the NodeAgent process.
  • Distribution of v3.x and v4.x administrative server functions improve fault tolerance and application performance. Each application server now includes a security server and a name service.
  • Addition of Java 2 security support.
  • Inclusion of EJB 2.0 standard support, which includes support for Message Driven Beans and the optional installation of an embedded messaging provider.
  • Inclusion of EJB deploy, leveraging the standards-based Eclipse framework.
  • Enhancement of ORB technology to support new standards (for example, CSIv2), as well as prior standards for version interoperability; for example, Secure Association Service.
  • Implementation of the JMX standard as the administration interface, which moved an administration process into each application server. Each application server can now be directly managed, in addition to centrally managed (in WebSphere Application Server Network Deployment).
  • Addition of installation verification classes that interface with the IVT tool.
  • Inclusion of Embedded Messaging to provide session persistence without a database.

Characteristics of change in disk usage:
  • 48% more class files
  • 70% more JAR files
  • 28% more disk space used (without installation of Embedded Messaging)

Characteristics of change in memory usage:
  • 21% more classes loaded during startup
  • 40% more live objects created during startup
  • Note: startup time was improved through performance tuning in fix pack 2.

Aside from these specific changes, WebSphere Development endeavors to keep the memory usage consistent from release to release.

Minimizing Disk Space and Memory Used
You can minimize disk space and memory used in a specific configuration by selecting only the WebSphere Application Server components required to support deployed applications.
For example, Samples and Embedded Messaging are components frequently omitted from production configurations.

Components can be installed independently into a WebSphere Application Server configuration when they are needed.

More Information About Performance Tuning
  1. Go to the WebSphere Application Server Support Page: http://www-306.ibm.com/software/webservers/appserv/was/support/
  2. In the "InfoCenter" section, select "Product Information."
  3. Select the appropriate Information Center for your needs.
  4. Click Performance on the Information Center main page.
 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers Runtimes for Java Technology Java SDK
 
Historical Number
PMR 39063
278
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > General
Operating system(s): Windows
Software version: 5.0
Software edition:
Reference #: 1138965
IBM Group: Software Group
Modified date: Jan 14, 2004