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All Things WebSphere

Concerns and issues relating to all versions of WebSphere Application Server

Tuesday, May 10, 2011


WebSphere Application Server - Performance considerations for deploying very large Java Enterprise Edition (JEE) applications

Please consider the following when developing and deploying very large applications (> 30,000 classes) bundled in one ear file.

The cost of having a large number of classes depends strongly on details of how the classes are present in the application, and whether Java EE5 features are enabled, and whether scanning is left enabled on all of the classes.

1) If the classes are exposed in a web module archive "WEB-INF/classes" directory, that will cause very large slowdowns.  The converse is for the classes to be in a JAR, either in a simple utility JAR directly contained by the application archive (EAR file), or for the classes to be contained within an EJBJar, or for the classes to be contained in a JAR beneath a web module archive "WEB-INF/lib" directory.

2) If javaEE5 processing is enabled for the classes, either because the classes are present in a javaEE5 enabled EJBJar or WAR, that will cause large slowdowns. The converse is for the classes to be present in a location which will not be scanned, for example, if there is a "META-INF/application.xml" for the EAR, and if all of the modules use a pre-javaEE5 version, or if all of the modules are marked as metadata-complete.

3) Even if javaEE5 processing is enabled, if a large subset of the classes do not require annotation scanning, that can be disabled using special properties in the application and module "META-INF/MANIFEST.MF" manifest files.

4) If using WAS version 7, please upgrade to fixpack or later.  We put in some optimizations in to make the reading and writing to disk of applications much more efficient.  Large apps (like Commerce) that are over 100 MB in size deployed 30-40% faster.

5) Check if the application is EE5 (in the application.xml, look for the version= tag).  If so, check if there are any WAR files inside the EAR that contain numerous JARs under WEB-INF/lib.  If those are present they can increase deployment time significantly.  There is a tuning option available to help, and it's documented here PK87053: JAVA ENTERPRISE EDITION VERSION 5 APPLICATIONS TAKE A LONG TIME TO DEPLOY http://www-01.ibm.com/support/docview.wss?uid=swg1PK87053

When deploying the application, there will be an unavoidable cost of copying the application files during deployment, which will be proportional to the total size of the classes (but not proportional to the number of classes, unless these are exposed in a WEB-INF/classes directory).  If the average class size is, say, 3K, and if there are 30K classes, then that will put the application size at at least 90M, which will take time to expand and to copy into the deployment location.  However, that cost is only during deployment.

 Note of thanks to Thomas Bitonti and David W. Hare for providing this information


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