How can you force recompilation of jsps in JBoss 4.2?

Question

I hit on this nasty behavior on JBoss 4.2 in QA, and I want to nip it in the bud before we go into production and find some other corner case.

A jsp calles a method that had the following signature:

 public void methodName(String arg)

This was changed to:

 public void methodName(String arg, Object... args)

A pre-existing JSP called this method via:

 methodName("param");

On deployment of the modified code, JBoss did not recompile the JSP and this caused a crash in QA. Adding a silly comment to the jsp fixed the problem (JBoss recognized that the JSP changed and recompiled it).

Is there a setting on JBoss to force recompilation of JSPs on restart?

EDIT: To clarify some points in the answer, the setup is that the JSPs are part of a war which is part of an ear. The ear has all classes in it, in a jar.

Regarding the desire to pre-compile, if the system doesn't think that the jsp needs compilation, will pre-compile force recompilation? It doesn't seem so. The error here is not a compliation error, it is a method invocation error because of the "changed" (at the byte code level, not really at the code level) method signature.

Addendum: Note that we experienced in production recently that even with the accepted answer's flag set the JSPs did not recompile, even though the JSP did in fact change. Major bug there, but regardless, JBoss was shutdown normally. At this point it is getting to be an old version of JBoss, but if you are still using it, deleting the content of the work and tmp directories is the only way to be sure.

I'm not changing the accepted answer simply because it really gets to the point of what the question was looking for. JBoss bugs are kind of a separate issue.

Answer 1

If the JSPs are part of a WAR that is part of an EAR that is being deployed as a jar, then I'm not clear why your JSPs are not being recompiled. Don't the JSPs in the war file have newer timestamps than their JBoss-compiled class files from the last deploy? If not, couldn't you touch the JSPs as part of building the WAR/EAR before deploying. [I'm referring to using the Unix "touch" command, not manually touching each JSP file.]

Alternatively, the DeleteWorkDirOnContextDestroy setting in $JBOSS/server/default/deploy/jboss-web.deployer/META-INF/jboss-service.xml may be what you are looking for. It is false by default, but setting it to true may be what you need. I think this should delete the JSPs' class files on redeploy so that they get recreated upon first access of each JSP.

See https://jira.jboss.org/jira/browse/JBAS-3358 for more info.

Answer 2

I don't know of a setting, but deleting the generated Java class file in the work directory of your JBoss instance will cause the JSP to be recompiled the next time it is called.

Answer 3

You coudl alter the JBoss startup scripts to explicitly delete the "tmp" and/or "work" directories, where the compiled JSPs are stored. JBoss would then have no choice but to recompile them all.

Not subtle, but it would do the job.