NoClassDefErrors found in Tomcat 5.5

[Thulasiram Gopalakrishna <th...@gmail.com>]

Dear friends,

In a set up, where we have Tomcat 5.5 running on Java 1.6, I have been seeing NoClassDefErrors thrown for a  set of classes. I am not too sure as to why these exceptions occur? And this particular error happens at times, and when it happens, Tomcat will not respond.The packaged jar files are found in the CLASSPATH.

I  am suspecting about Garbage Collection and as JVM might have unloaded some of these classes. But, I am not too very sure at the moment. 

Is there anything in Tomcat's Classloading mechanism that can provide a clue? 

Any help, providing direction, to attack this issue, is deeply appreciated.

Regards,
Thulasiram

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Re: NoClassDefErrors found in Tomcat 5.5

[Mark Eggers <it...@yahoo.com>]

Thulasiram,

1. Tomcat 5.5.x (what is your x?) is no longer supported
2. Java 1.6 is no longer supported unless you have a contract
3. CLASSPATH is almost never the place to put web dependencies

Steps to address the issue:

1. Move to the latest Tomcat 6 or Tomcat 7 (preferably 7)
2. Move to the latest JRE (1.7.0_40)
3. Remove extra stuff from your CLASSPATH
4. For your application dependencies
    a. put all classes in WEB-INF/classes
    b. put all libs in WEB-INF/lib
    c. Container-managed resources go in CATALINA_BASE/lib

Most people writing about issues with classpath are using Eclipse. Are 
you trying to run this from Eclipse?

If so, follow the above, and do the following:

1. Use the latest (or next to latest) J2EE version of Eclipse
2. Use either Eclipse's project structure or Maven
    a. If you're using Maven
       i. Use the latest Eclipse
       ii. I like JBoss Tools plugin as well
       iii. Maven takes care of dependencies for you
    b. If you're using the standard Eclipse environment
       i. extra libs go in WebContent/WEB-INF/lib
       ii. extra classes go in WebContent/WEB-INF/classes
       iii. Eclipse adds these to the build path for you
       iv. Eclipse places compiled sources in classes
3. Add the Tomcat server to a Servers project (follow the wizard)

just my two cents . . .
/mde/

On 9/29/2013 9:38 AM, Thulasiram Gopalakrishna wrote:
> Dear friends,
>
> In a set up, where we have Tomcat 5.5 running on Java 1.6, I have
> been seeing NoClassDefErrors thrown for a  set of classes. I am not
> too sure as to why these exceptions occur? And this particular error
> happens at times, and when it happens, Tomcat will not respond.The
> packaged jar files are found in the CLASSPATH.
>
> I  am suspecting about Garbage Collection and as JVM might have
> unloaded some of these classes. But, I am not too very sure at the
> moment.
>
> Is there anything in Tomcat's Classloading mechanism that can provide
> a clue?
>
> Any help, providing direction, to attack this issue, is deeply
> appreciated.
>
> Regards, Thulasiram


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