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Subject DO NOT REPLY [Bug 48097] New: NoClassDefFoundError on first access of first jsp
Date Sun, 01 Nov 2009 19:06:10 GMT

           Summary: NoClassDefFoundError on first access of first jsp
           Product: Tomcat 6
           Version: 6.0.20
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Catalina

Created an attachment (id=24452)
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simple webapp with one jsp and one class in one jar, reproducing the error

I've had a strange situation getting NoClassDefFoundErrors on a particular jsp
page (which happened to be the index.jsp page). The class it claimed to not
find is a simple session bean class within a jar in the WEB-INF/lib folder. The
strange thing is that it gave this error only when this page was the first one
accessed after a tomcat restart. If any page was accessed before it, it would
work properly. But if this page was accessed first, then no matter what pages
were later accessed, the error remained in place. So the error/success state
was determined by whichever page was accessed first ater the tomcat restart,
and remained in the same error/success state for as long as tomcat was up,
regardless of anything happening later on (until the next restart)

This seems to be some sort of class-loading oder-of-initialization bug, but is
entirely consistent when the pages are accessed in this order after a tomcat
restart. It drove me nuts for a while, since the main application page was
showing an error after every restart, but I eventually stumbled on a strange
workaround: changing the order or a couple of lines in the jsp, involving the
useBean directive and access to java's URI class. with the order changed, the
error never happens. with the order returned, the error is reproduced as
described above.

I've managed to distill a simple scenario which reproduces this error - a short
jsp and a trivial bean session class - attached. I reproduced this on a fresh
installation of Kubuntu 9.10 in a virtual machine, with sun jre 6 and tomcat6
installed. I didn't change any configuration, just replaced the ROOT sample
webapp with this one, restarted tomcat, and browsed to
http://localhost:8080/index.jsp. Remember u have to restart tomcat after every
change to the jsp if u want to recreate the bug, because simply changing it and
refreshing the browser will always succeed.

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