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From Tim Funk <funk...@joedog.org>
Subject Re: Measuring latency between tomcat instances
Date Wed, 21 Jan 2004 13:45:52 GMT
Instance B knows nothing about instance A. Instance B is only serving 
responses to instance A. Instance A might do a lot of work before and after 
it talks to instance B which might make instance B look bad even if that is 
the short part of a transaction.

The only gotcha is if client side javascript were introduced. The javascript 
might be doing calls back to A introducing a nasty piece to the puzzle.

-Tim

Jeremy Nix wrote:

> Okay, let me pose another (slightly differenc) question.  Say that
> instance (A) and (B) are separate institutions, independent from each
> other.  Same scenario as before.  How could instance (B) (the responding
> instance) be able to measure latency in instance (A)?  The reason I ask
> is related to an issue that has been reported to me, but I am unable to
> understand how the latency was measured.
> 
> 
> _________________________________
> Jeremy Nix
> Southwest Financial Services, LTD.
> Jeremy.Nix@sfsltd.com
> (513) 621-6699 ext.1158
> 
> 
> 
> -----Original Message-----
> From: Tim Funk [mailto:funkman@joedog.org] 
> Sent: Wednesday, January 21, 2004 8:26 AM
> To: Tomcat Users List
> Subject: Re: Measuring latency between tomcat instances
> 
> 
> LOG4j might be nice kludge for this. On tomcat A, time the appropriate
> events 
>   on how long it takes to do stuff on tomcat B.  Then log it in a
> specially 
> formatted message. (mylogger.log("time: " + timeTaken) Then do the same
> on 
> tomcat B. Its easier to do on tomcatB since you can use a Valve or
> servlet 
> filter and stay out of the business logic.
> 
> I say LOG4J since it provides asynchronous loggers (Unless the
> performance on 
> the non-asynchronous loggers are neglible in this case). But with LOG4j
> (or 
> insert logging framework here) - you can use it to write to any log file
> or 
> format you want. So your normal error messages can go to one file while
> these 
> special messages can go to a differnet file/database/...
> 
> ------
> 
> Or you can compare acces log entries since it does offer a %T option for
> time 
> taken.
> 
> -Tim
> 
> Jeremy Nix wrote:
> 
> 
>>We have an instance where tomcat instance (A) is communicating with 
>>tomcat instance (B), where instance (B) is located at another site. 
>>Instance (A) formulates a request to instance (B) and instance (B) 
>>responds with some valid response.  Now, my question is, from a 
>>standpoint of instance (B), is it possible to measure latency?  If so,
> 
> 
>>how?
>>
> 
> 
> 
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