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Hey there. I'm grasping at straws and am hoping someone remembers their
JES2 internals. I've looked in the JES2 Innita Tuna? manual (Ch 2.
Controlling JES2 processes) without success and can't find a RedBook
that helps. Perhaps someone remembers or can point me to a Fine
Manual.(I'll ETR otherwise.)
Background: z/OS v1.7, DB2 v7. During our (peak) registration periods,
we experience occasional, un-explainable slow-downs in 1-3 minute bursts
on the order of 3-5 in a 2-3 day period. To date, no particular culprit
has been positively identified. Aside from 100% CPU & 20+ un-dispatched
tasks, one reported symptom is an increasing number of DB2 threads (from
OmegaMon) waiting for Stored Procedure start-ups ie. for WLM to start
another address space. (@15 TCBs each) Sure enough, once the dust
settles, there can be 10+ WLM address spaces that slowly disappear as idle.
This line of inquiry (among others) focuses on JES2's internal readers.
We suspect processes generating e-mail to students with a 1-1 ratio of
jobs to messages ie. 1 job=1 e-message, using SYSOUT=(*,INTRDR). (We're
also pursuing multi-step jobs since $HASP050: >90% JNUM has already been
encountered.) In a given scenario, we could have 200+ jobs with e-mail
(bulk to a large class) directed at INTRDR while WLM is trying to start
1-5 Stored Procedure address spaces via STCINRDR.
So, the question is, presuming it's already working on INTRDR, how does
JES2 contend with this load? Are all the jobs in INTRDR converted then
JES2 switches to STCINRDR? Does STCINRDR have precedence for JES2 and
INTRDR is interrupted at the next JOB card? Are they simultaneous with
their own TCBs? Curious minds would like to know. (or even hear
speculation...)
As mentioned before, if there's no satisfactory consensus, I'll pursue
an ETR and relay the response. Tks much folx.
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Neil, what's the observed CPU utilization of your JES2? If it's not
really high, I'd suggest you look elsewhere. It's been a long time since
I looked in this area, but IIRC, STC's take a slightly different path
through JES2 processing. A more likely culprit might be AS-Create; even
more likely, IMHO, a ENQ/DEQ contention issue.
JES2 uses something called a PCE, a Process Control Element, to
represent multiple INTRDR's, rather than TCB's. They're managed
internally by JES2 and typically run fairly quickly. I'm not sure, but I
think conversion is done under a PCE as well, so the CPU time involved
would be attributed to JES2. How many INTRDR's do you have defined? I
don't know if you can specify the number of conversion tasks allowed or
not; last time I tried to care, I couldn't specify a number for
conversion tasks, but I could specify up to 10 INTRDR's.
Without a much broader picture of your system, it's going to be hard to
make any definitive diagnosis.
Are you running RMF? I like RMF, with a 10-minute recording interval. If
you'll do that, over a period where you're affected by this issue, and
send me the reports, beginning two periods before and ending two periods
after, I'll try and give you some pointers. (ZIP the reports, please.) :-)
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