Classloader problems Tomcat 6 javagent

Question

I am using Salve Dependency Injection library that instruments the byte code of the web application. I specified -javaagent in Tomcat VM options and pointed it to the Salve agent jar.

The agent jar gets loaded, but then it throws a java.lang.NoClassDefFoundError unable to find classes that are in other Salve jars which are located in WEB-INF/lib folder of my web app.

I can solve this problem by putting those JARs in Tomcat/endorsed folder. However, some of those jars depend on third-party libraries, such as Spring and servlet-api.jar. Therefore, I am forced to put all these dependencies in Tomcat/endorsed as well.

Could anybody suggest a better way for handling dependencies of a Tomcat javaagent?

Thanks.

Answer 1

This sounds very weird. Agents usually do not depend on other classes, as it would make them completely useless. I think you are misunderstanding the error. Is it possible that the dependency is from the instrumented classes and wrong classes are ending up instrumented?

Answer 2

Salve? WTF? Use AspectJ.

"Dependency injection framework that depends on Spring" - o_O ?!

Answer 3

Salve library consists of several JARs. Some of them depend on third-party libraries, such as Spring. I ended up moving those JARs from tomcat/endorsed to my webapp's WEB-INF/lib. My findings and the final working directory structure are documented here?