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From Madhuri Patwardhan <madhuri_patward...@yahoo.com>
Subject Re: what exactly happens when timeouts are set and tomcat has outofmemory errors.
Date Mon, 03 Aug 2009 23:06:46 GMT

Before I set the timeouts thats how it worked. The tomcat instance in outof memory state would
be eventually marked in "ERR" state. I thought by using timeouts it would set it to "ERR"
state early.

I do need to restart the tomcat instance in outofmemory error but how would I know tomcat
instance is in that state unless I keep checking logs of all tomcat instances. I used the
"ERR" indication on jkstatus page to know if there is something wrong with tomcat instance.

Actually, before setting the following timeouts, I would see tomcat instances get marked to
"ERR" state. After, setting these timeouts that is not happening as much as it happened before.
After setting these timeouts I have got lot more error reports of website access errors.

Do you know anything about recovery options?

Thanks,
Madhuri

--- On Mon, 8/3/09, Mark Thomas <markt@apache.org> wrote:

> From: Mark Thomas <markt@apache.org>
> Subject: Re: what exactly happens when timeouts are set and tomcat has outofmemory errors.
> To: "Tomcat Users List" <users@tomcat.apache.org>
> Date: Monday, August 3, 2009, 6:49 PM
> Madhuri Patwardhan wrote:
> > Hi,
> > 
> > Can somebody go over the details of what exactly
> happens when tomcat instance has outOfmemory errors and
> there are following timeouts set in a loadbalancer worker
> config. 
> > 
> > This is my understanding.
> > 
> > ping_mode=A, ping_timeout=10000, reply_timeout=60000
> and recorver_options=3
> > 
> > If the timeouts are set as above then CPing/Cpong test
> for connect and prepost will work. When a new real request
> is sent to this tomcat instance, it should hit reply_timeout
> because it has outofmemory errors.
> 
> That depends on the state of the JVM. It might appear to
> work normally,
> it might fail to respond at all. Once on OOM has occurred
> Tomcat has to
> be assumed to be in an unknown state and should be
> restarted. I have
> seen Tomcat instances apparently recover from an OOM. It
> all depends why
> the OOM occurred and what Tomcat was doing at the time.
> 
> > Then depending on no. of retries set (it is default,
> for me so 2), this instance will be tried once again. Second
> time also it should not get reply within reply_timeout and
> at that point it should be marked in "ERR" state. 
> > However, I don't see that. I don't see it being marked
> in "ERR" state. The state is still "OK" inspite of this
> tomcat instance having outofmemory errors. Could somebody
> explain what am I missing?
> 
> In short, you are incorrectly assuming that once an OOM has
> occurred
> Tomcat will no longer respond to requests.
> 
> Mark
> 
> 
> 
> 
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