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From Pid <...@pidster.com>
Subject Re: Need help tracking down a strange Threading issue in Tomcat 6, but not 5.5
Date Wed, 23 Jun 2010 07:59:19 GMT
On 22 Jun 2010, at 22:38, Mick Knutson <mknutson@baselogic.com> wrote:

> have an application I am trying to move to Tomcat 6.0 from Tomcat 5.5.

Which versions exactly, (- it does matter)?
Also OS, JVM and any other relevant app versions.


> This
> is a VXML Voice Browser application.
> 
> In this app, the general flow is:
> 
>   1. Voice Browser makes http request to jsp
>   2. jsp might call Service Object
>   3. Service Object creates new Thread to call external Webservice
>   4. If the service fails, then the Jsp calls another webapp to send the
>   same request pseudo asynchronously.
>   5. 2nd webapp call external webservice.
>   6. JSP returns.

Performing the logic in a Servlet would be more elegant. ($0.02)


> 
> This works fine (not great, but does function) in PROD now on TC 5.5
> 
> But when I move this to TC 6, I have a strange issue where there are User
> created threads making external webservice calls to another server, and they
> stop spawning new threads, and the existing threads seem to complete, but do
> not allow anymore to be created.

Take a thread dump, see what they're all doing during the slow down.

> Tomcat is set to handle 350 threads.

How have you done this and are you expecting it to limit the number of the application (as
opposed to Connector) threads?

> When this happens
> 
>   - There are about 100-200 total threads.
>   - Memory @ 40% used
>   - CPU @ ~6%

Which memory? Server or heap? 
What are your heap settings?


p

> It almost appears as though TC just is not accepting anymore new requests,
> for ~5 minutes. Then it comes back to life. But we can not leave this
> running as the caller experience is not good.
> 
> On lower volumes, say < 100 requests, we do not see any issue at all.
> But TC 5.5 is taking ~100-140 requests currently and does not have thee
> failures.
> 
> I can attach images, JVMVis snapshots, and a word doc showing several WILY
> report graphs to see if I can get some help on this please.
> 
> I have been working on this for a solid 3 weeks and no luck.
> 
> ---
> Thank You…
> 
> Mick Knutson, President
> 
> BASE Logic, Inc.
> Enterprise Architecture, Design, Mentoring & Agile Consulting
> p. (866) BLiNC-411: (254-6241-1)
> f. (415) 685-4233
> 
> Website: http://www.baselogic.com
> Blog: http://www.baselogic.com/blog/
> Linked IN: http://linkedin.com/in/mickknutson
> Twitter: http://twitter.com/mickknutson
> Vacation Rental: http://tahoe.baselogic.com
> ---

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