RE: Web Service slow on first call of the day

["Mitchell, Dana" <dmitche@xxxxxxxxxx>]

Michael,

We experienced (and actually still are) something like this.   The application in question is an ODBC call to very large complex SQL commands.   After applying maintenance, coming up to current cumulative and group levels,  we experienced a drastic increase in CPU usage for these queries.  According to IBM, the increased time is spent in Plan Selection, in our case using multiple minutes of CPU time.  Then once through the selection, the queries run in sub second response time like they did before the maintenance was applied.

Does this sound like your scenario at all?

Dana

-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Koester, Michael
Sent: Monday, March 09, 2015 7:59 AM
To: midrange-l@xxxxxxxxxxxx
Subject: Web Service slow on first call of the day 

(cross-posting to WEB-400)
I have developed a web service with the Integrated Web Services facility (IWS) that is almost production ready, but I'm noticing that the very first call of the day takes 30-45 seconds to return a response.  A subsequent calls provide sub-second responses, and that continues throughout the day.  I'm normally pretty patient, but this will be used to provide data to a customer-facing web site, and if I was the first customer of the day to the web site, I'd give up if it hung for more than 10 seconds -- by 30 seconds I'd be off doing other things for sure.

My questions are:
1. What are the likely causes for the delay-on-first-call behavior?
2. What might I do to either eliminate the problem, or perhaps simulate a call on web server start-up, so that the first customer gets an acceptable response time?



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