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From André Warnier ...@ice-sa.com>
Subject Re: very slow class loading on initial JSP/servlet request after restart
Date Fri, 20 Feb 2009 12:37:15 GMT
Caldarale, Charles R wrote:
>> From: Sam Hokin [mailto:sam@ims.net]
>> Subject: very slow class loading on initial JSP/servlet
>> request after restart
>>
>> The server that's being a problem is a Dell PowerEdge
>> 1950, quad dual core.
> 
> Since I could never believe anything bad could be caused by chocolate (especially dark
chocolate), let's go for something else.
> 
> 1) What are the servers that don't have a problem?
> 
> 2) How much RAM is on each server?
> 
> 3) Is the JDK 32- or 64-bit on each server?
> 
> 4) What's the Java heap size for Tomcat on each server?
> 
> 5) Are you using the same file system on all three servers?  What is it (ext3, reiser,
???)?
> 
Dropping the dark chocolate then from my suspicions, and notwithstanding 
the above fact-finding questions, I still think the reindeers are 
suspect, such as 4 of them pulling in opposite directions.

It kind of reminds me of my xml-parsing webapp of a while ago, which 
took (and still takes) an inordinate amount of time to load initially 
(10 minutes or so), but then has a perfectly acceptable reponse time 
after that.  That is on a single slow cpu and with less RAM than Chuck 
has in his portable phone, but it may still be a good analogy since 
these elements merely exacerbate the problem.
What is that webapp (or these classes) really doing when initially 
loading, that they are no longer doing afterward ?
On my system also, the log message indicating that the application is 
"loaded" comes only after these initial 10 minutes during which the 
whole Tomcat is close to inoperative.

Since we have 4 processors here (do we, really? I am not so familiar 
with the multi-core architecture), can each of these processors be 
running a thread of these apps/classes, where on a single processor 
there would be only one thread running ?
And would it be possible that each of these cpus/threads is doing 
something that severely competes with the others trying to do the same 
thing at the same time ? (such as using a lot of memory, and resulting 
in massively swapping in/out).  There may be 4 cpus, but there is still 
only one each of the other resources, like RAM.
Would running Jconsole while the app is loading help ?


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