ca.portal.admin

Re:now to prevent space management page deadlocks???

Discussion created by ca.portal.admin on Jul 12, 2010
i think we all know the bad programming code that can lead to db-key
deadlocks - but are SMP deadlocks just a matter of coincidence?
can they just occur because of where record occurrence STORES or DELETES
(or MODIFYs) are intended to take place?


thanks,
Chris Hoelscher
IDMS/DB2 System & Database Architect
Humana Inc
502-476-2538
choelscher@humana.com

you only need to test the programs that you want to work correctly




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Re: now to prevent space management page deadlocks???
"Chris,

They sure can. Try doing an EXTEND SPACE on a busy area without following =
it up with a proper UNLOAD/RELOAD, and watch what happens. It's not pretty=
.

You will see a series of lock manager abends on one space management page. =
After a while, they will switch to the next SMP. Then to the next one.

These are technically not deadlocks, but lock manager timeouts.

You can get a similar effect by defining the storage mode of a busy record =
type as DIRECT or VIA an index. (By ""busy"", I mean lots of stores.) Chang=
ing the storage method to a random CALC key will usually solve the problem.

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