RE: Data queue space

Alistair Rooney  said:

> I'm so glad you touched on journaling with MQ. We are having 
> a hellish time
> with all MQ programs going into a lock wait for 10-30 
> minutes. This seems to
> be every time it does a journal detach. It's causing havoc 
> with our timings.
> IBM say that there are PTFs available for V5 but we are on 
> OS/400 V3.7 and
> to run V5 of MQ we would need to upgrade to OS/400 4.n.
> 
> Do you know of any workaround. The journals are managed by MQ 
> internals
> which makes things a bit scary.

This sounds a bit familiar.  We haven't used OS/400 V3R7 for a few
years, but we did have some severe locking problems in MQ on a large
machine which was at V4R1 or 2.  The best IBM were able to tell me was
that it might be to do with the number of MQ messages per syncpoint.  A
syncpoint is better known as a commit cycle.  So, how many messages do
you process between commits?  At the time we were having the problems,
which was December last year, our contact at IBM said that their
performance people recommended a maximum of 50 per syncpoint.  This
assumes, of course, that you are using syncpointing.

Anyway, we installed various PTFs over a period of several months, and I
think eventually it must have got fixed, because I haven't heard of it
happening in quite a while.

That said, if your problem is definitely linked to journal receivers
being detached, you could increase the receivers' threshold value -- at
least, you ought to be able to; I cant't find out how you would change
it, so perhaps it can only be done on create.  Hmm...

Also, I was wrong about 5.1 not using journalling; its just that the
journal and receivers are now in a queue-manager specific library,
instead of QUSRSYS and QMQMDATA respectively.  You can have multiple
queue managers at 5.1.

HTH.

Cheers,

Martin.


--                                                                     
Martin McCallion                 
Midas-Kapiti International
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