Slow running WLM store procedure

John Alexander

Slow running WLM store procedure
Hi Avram,
Really appreciate your reply, it gives us something to look at, I will
pass this to our DB2 Sysprog to verify the Java NUMTCB I am not sure
where they are kept. I checked the Zparm but couldn't find any
parameters relating to Java, and the DB2?WLM address space has NUMTCB=8
, but I think that is for the number of threads for the address space
itself & not java related.
In relation to the Zaap , our MVS systems Sysprog advised that we can
not turn it on until we pay IBm the one time change.

Regards
John


-----Original Message-----
From: Avram Friedman [mailto:[login to unmask email]
Sent: Thursday, 13 December 2007 1:47 AM
To: [login to unmask email]; Alexander John
Subject: Re: Slow running WLM store procedure

John
I have no reason to doubt what your performance people say,
however there is a common reason why JAVA stored procedurs tend to run
slowly at first.

A. The JVMs are huge and a seperate copy is loaded for each TCB in the
WLM
address space.
B. If you store your JAR files in DB2 (common) at each WLM start up the
JAR
files are copied from the catalog to USS temp files
C. Any abend (you dont have to see an error message) causes everything
in
the WLM to be deleted and reloaded.
D. Many OMVS environments are only tuned for minimum use by TCP/IP


Are you mesuring the preformance of the first schedule of a JAVA stored
procedure or the nth instance or the average of a signifigant number of
instances? It makes a difference.

The eaisest way to test this is to reduce the number of TCBs in the JAVA

WLMs. Quick and dirty you can just hard code the the number in the WLM
jcl.
I would give 2 or 3 a try.

Has any one mentioned buying a Zaap?

Regards
Avram Friedman

On Wed, 12 Dec 2007 01:26:34 +0000, John Alexander
<[login to unmask email]> wrote:

>Hi colleagues,
>
>We have a new distributed application that is using WLM stored
procedures,
>connecting to the DB2 via JDBC calls from a Web Methods server .
>Recently one of the stored procedures had a performance problem during
a
>test run, and our DB2 & MVS sysprogs concluded that the store proc
was
>running in a low service class based on the 'callers' userid ! ,
rather than
>the service class assigned to the DB2?WLM address space it was running
>in ! .. I have not been able to verify this & frankly I am not sure
where to
>even look, but if the analysis is correct does anyone know what we
need to
>do in order to have the stored procedures run under the service class
>assigned to the DB2?WLM address space ?
>
>This is not an area I know well and your feedback, & thoughts would be
>greatly appreciated.
>
>Also if we want to be more granular in assigning WLM service classes
for
high,
>medium & low priority store procedures, then how can we best achieve
this .
>
>Ps. we are on DB2 z/OS V7, z/OS 1.7, and JDBC type 4 driver.
>
>Regards
>John Alexander
>Woolworths
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Robert

Re: FW: Slow running WLM store procedure
(in response to John Alexander)
John,

Look in the redbook 'Through the call and beyond' in chapter 20 about WLM
and SP's. To be specific, at page 323 you can find the note:

An installation assigns SCs to individual pieces of work, but not to individual
stored procedures. It is the caller of the stored procedure that determines the
SC the stored procedure runs under.

Regards, Robert

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