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Java agent WebSphere class cache behaviour

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Article ID: 112755

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Updated On:

Products

CA Application Performance Management Agent (APM / Wily / Introscope) INTROSCOPE

Issue/Introduction

IBM WebSphere employs a method of class caching for performance reasons, loading bytecode into a cache persisted on disk that can be shared by mutliple applications using the same JDK.

Because the APM Java Agent performs bytecode instrumentation, references to the Java Agent code are also stored in this cache

When updating the Java Agent version, the cached version of the agent's code may have been changed.

This can lead to conflicts causing problems with both the agent's and monitored application's behaviour.

Environment

Release:
Component: APMISP

Resolution

The recommendation would be to clear the WebSphere class cache after every change to the agent code, particularly where upgrading the version, but also advisable where applying individual fixes
 

Additional Information

IBM information on clearing WebSphere class caches:

http://www-01.ibm.com/support/docview.wss?uid=swg21607887