discussion on webapp reload in production environments

[Allistair Crossley <Al...@QAS.com>]

Hi,

Yoav, you suggested we should pick up this thread here in the list rather than the bugzilla report at http://issues.apache.org/bugzilla/show_bug.cgi?id=26372

I have copied the last 4 replies for any interested parties to start following this thread.

I look forward to hearing the position on webapp reloading in terms of desirable behaviour and the specification when you have time to do so.

All the best, Allistair.

YOAV
I'd point out it's only 'dying' when you're trying the 
app reload, nor normal usage.  This feature is not mandated by the Spec so we're not obliged to provided it in the first place: it's caused mostly trouble 
and has very limited usage in production environments.  So if you have patches 
for it, that's great, but the common usage scenario for Tomcat doesn't include 
webapp reload, and so doesn't suffer from this issue at all.

ME
I am interested in your comment that reload of webapp is mostly trouble and limited in production environments though. My understanding was that if you 
want to make a build to production or a patch of some files, you would use ant 
or similar as we do here to reconstruct the WAR to deploy. Does this not 
require tomcat being able to reload? In fact, we tell the business the intranet 
will be down for 5 minutes and post a message page up for inbound requests. We 
stop tomcat, delete the old war and expanded war files and place the new war 
and startup tomcat again. We constantly get irked by the fact that if a bug is 
on production we have to wait until the evening to patch it whereas our ASP coutnerparts can so easily hot-patch. We also use JSP precompilation to improve 
performance so it's not so easy to patch JSPs either.

REMY
I hope hot deployment and redeployment is a reality. However, there are issues
when the webapp tries to interact with some services which reside in the system
classloader (logging here). Packaging webapps a little differently could solve
the problems for now.

YOAV
Allistair, I'll be glad to continue this discussion on the mailing list and try 
and explain why I think reloading an app in-place has only limited usage in production environments.  This (Bugzilla) is not the right forum for 
discussions.


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