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Date: Tue, 21 Aug 2007 13:20:22 +0100
From: Paul Singleton <paul@jbgb.com>
Organization: Jambusters Ltd
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To: Tomcat Users List <users@tomcat.apache.org>
CC: mtitania@gmail.com
Subject: Re: Does anyone have an approach to checking if Tomcat instance is
 UP?
References: <d86773480708200748j53888b46j6f903129a9c12dc9@mail.gmail.com>
	 <DE7E6E8BAA40094BA978BAA6C4B046A6D8323B@LIN-EXCHPRD-01.us.nelnet.biz>
 <d86773480708201504l7346078aq4db76b9f7ea9bb1d@mail.gmail.com>
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Kim

Do you have reason to believe that the OutOfMemory exception
is due to:

  * some cumulative effect (e.g. memory leak), in which case
    you need to restart, preferably (just) before it happens

  * the qty of active sessions, so you need to load-balance
    when near some threshold (offload to a less busy server
    iff poss else "please come back later")

  * the complexity of some user's request, in which case your
    app isn't really "down" at all...

Paul


Kim Albee wrote:
> Tracy,
> 
> The JSP does a call to a method in our app -- which if it runs, that means
> the app is up and available -- the method does a simple query against the DB
> and then returns a status of OK if the method runs through just fine.
> 
> In our example from this weekend -- the health.jsp (which is the one that
> does this check) ran and returned a good result, but the main
> index.jspreturned the 500 error with the OutOfMemory exception.  So
> that is what is
> confusing here.
> 
> thanks,
> Kim :-)
> 
> On 8/20/07, Nelson, Tracy M. <Tracy.Nelson@nelnet.net> wrote:
>> How is your JSP checking your application?  Are you issuing a request to
>> your app and checking the HTTP status?  If so, why isn't it recognizing
>> the 500?  Or is the JSP in your application which is failing?
>>
>> | -----Original Message-----
>> | From: Kim Albee [mailto:mtitania@gmail.com]
>> | Sent: Monday, 20 August, 2007 09:48
>> |
>> | Repeatedly, that JSP will work, but the site is down because Tomcat
>> hit an
>> | OutOfMemory exception -- but our JSP (which is very small) still runs
>> | through it's process and returns that everything is happy.  Our
>> | application
>> | is up, but the 500 error is an OutOFMemory exception.
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> 


-- 
Paul Singleton
Jambusters Ltd

tel: 01782 750821
fax: 08707 628609
VAT: 777 3904 85
Company no. 04150146


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