Re: DTAARA Lock Issue?

Just a thought. It's been a while but a few years back
we used remote controllers that "appeared" to have issues
with timing. The remote session might be a tad late while
the local sessions "seemed" to update with no knowledge
of the remote session having locked the file/data area.
Again, just a thought but it all went away when we got
rid of those remote controllers. (Hopefully you don't use
remote controllers)






From: Roger Harman <roger.harman@xxxxxxxxxxx>
To: "RPG programming on the IBM i (AS/400 and iSeries)"
<rpg400-l@xxxxxxxxxxxx>
Date: 04/17/2017 12:39 PM
Subject: Re: DTAARA Lock Issue?
Sent by: "RPG400-L" <rpg400-l-bounces@xxxxxxxxxxxx>



Even if another program is incrementing the TMP#, it should not be an
issue as the data area is locked in the interim.

But... Buck's response prompted me to look at the other programs using the
data area. I need to dig deeper but I may have stumbled across something.
There *may* be an inconsistency with another program or two as far as
which value they're using - pre-increment or post-increment. It would
have to be the right confluence of events but that is possible and would
certainly explain it. As Buck said, I too have never seen an IN *LOCK not
lock.

Thanks all for your suggestions and tips.

Roger Harman
COMMON Certified Application Developer - ILE RPG on IBM i on Power



From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxx> on behalf of Charles Wilt
<charles.wilt@xxxxxxxxx>
Sent: Monday, April 17, 2017 9:51 AM
To: RPG programming on the IBM i (AS/400 and iSeries)
Subject: Re: DTAARA Lock Issue?

Think Buck is onto something...

Don't supposed the DTAARA is journaled?



On Mon, Apr 17, 2017 at 10:35 AM, Buck Calabro <kc2hiz@xxxxxxxxx> wrote:

On 4/17/2017 11:33 AM, Roger Harman wrote:

Two jobs retrieved the same number.

NOTE: Not my code - I just have to work with it. Why it has the

add/z-add combo is unknown.

** Data structure for next system number
** & next temporary reference.
D NextNum DS 14
D NSYSNA 1 7
D NSYSNN 1 7 0
D TMPRNA 8 14
D TMPRNN 8 14 0

C SrGetSys Begsr

C *DTAARA DEFINE SYSNBR NextNum

C *LOCK IN NextNum
C NSYSNA IFEQ *BLANKS
C Z-ADD 1 NSYSNN
C ENDIF

C NSYSNN ADD 1 UPDNBR
C Z-ADD UPDNBR NSYSNN
C OUT NextNum

C Endsr

Thanks for posting the code; I found it helpful. As a preface, I've
used *LOCK IN in many dozens of programs; over the 3 decades or so
probably a few billion update cycles. I've never, not once, seen an
issue with the OS. It's always been the program. That said, there is a
gotcha with this sample.

The data area is storing /two/ 'unique' numbers, right? You've been
focussed on two jobs that are trying to get a unique NSYSNN, but what if
there's a third job that's trying to get a unique TMPRNN? It could be
putting back an /old/ copy of NSYSNN as it increments TMPRNN.

Another possibility is a *PSSR/INFSR that somehow gets control between
the IN and the OUT. Seems unlikely, but we're looking for something
non-obvious, so I bring it up. The point is that job 1 might get number
555 and not increment it properly.

--
--buck

Try wiki.midrange.com!

--
This is the RPG programming on the IBM i (AS/400 and iSeries) (RPG400-L)
mailing list
To post a message email: RPG400-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/rpg400-l

RPG400-L Info Page - midrange.com
lists.midrange.com
To unsubscribe from RPG400-L, get a password reminder, or change your
subscription options enter your subscription email address:

or email: RPG400-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/rpg400-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: http://amzn.to/2dEadiD