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From Jess Holle <je...@ptc.com>
Subject Re: Tomcat 6.0.16 Startup Listener
Date Mon, 11 Feb 2008 21:52:11 GMT
Mark Thomas wrote:
> Jess Holle wrote:
>> Stusynski, Dan wrote:
>>> Tomcat devs,
>>> Noticed a curiousity during 6.0.16 startup after migrating from 6.0.14.
>>> Below is the startup logs for Tomcat 6.0.16 and am curious if this has
>>> been seen before (the duplicate Listeners)? This was not encountered in
>>> 6.0.14.
>>>
>>> Not only do we get these duplicate Listener messages for anything
>>> defined in web.xml but we also get it for anything we might define
>>> additionaly for our softwares Listeners.
>>>   
>> In other words, we also get such duplicate listener messages any/all 
>> <listener>'s in our web app's web.xml as well.  [Our web.xml is a 
>> perfectly valid 2.4 web.xml that worked fine with 6.0.14.]
>>
>> These info messages were certainly not present in 6.0.14 and even if 
>> they're bogus raise concerns and questions in 6.0.16.
> They are a result of the fix for 
> http://issues.apache.org/bugzilla/show_bug.cgi?id=44268
>
> It means that for some reason, Tomcat is trying to register the 
> listener more than once and subsequent attempts are ignored. This has 
> been the case for all of the 6.0.x series but now it is logged when it 
> happens.
>
> Looking back at the original issue 
> http://issues.apache.org/bugzilla/show_bug.cgi?id=3770 it is probably 
> occurring because the TLD is being processed twice.
>
> If this is generating a lot of noise then we probably need to look at 
> an alternative solution but one that addresses the noise and 44268 
> doesn't immediately jump out at me.
I'm unclear how <listener> elements in our web apps' web.xml are being 
processed multiple times.  I only declare a single <listener> element 
for each listener class -- nothing odd.  Processing them multiple times 
would seem to be a bug.  If Tomcat realizes its mistake and does not 
actually do this twice, then from an external perspective there is no 
bug (apart from a slight performance one possibly) -- but telling us 
noisily about it makes it an externally noticeable bug and erodes 
confidence in the overall server.

Given that our web app didn't mention anything about 
"listeners.ContextListener" or "listeners.SessionListener" I have to 
assume that this also is a bug -- in that our app never asked to define 
these at all, much less twice.

I'd like to know (1) why this stuff is being attempted twice, (2) 
whether it can be avoided from our end somehow, (3) whether there are 
any side-effects [besides a minor delay in startup], (4) whether a 
near-term fix is likely, and, lastly, (5) how we can shut up just this 
message if there's no better fix in the short term offing.

--
Jess Holle


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