RE: RPG400-L Digest, Vol 17, Issue 252

I use trigger program on the file being written to writing out the changed
record before and after image and the program making the change along
with user details program name and timestamp so I can track who and what is happening

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Sent: 15 May 2018 18:00
To: rpg400-l@xxxxxxxxxxxx
Subject: RPG400-L Digest, Vol 17, Issue 252

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Today's Topics:

1. One Write, two records.... (Costa Marks)
2. Re: One Write, two records.... (Craig Richards)
3. Re: One Write, two records.... (Joe Pluta)
4. Re: One Write, two records.... (Richard Reeve)


----------------------------------------------------------------------

message: 1
date: Tue, 15 May 2018 12:08:32 +0100
from: Costa Marks <markscostas@xxxxxxxxx>
subject: One Write, two records....

Hello,

The whole team I work with is facing a weird issue.

Program A loops per order and calls program B, program B is doing just a
write to a file (order lines) using the input parms from A.

Occasionally though, program B is writing 2 lines (duplicate) for some of
the order lines, not all. By deleting the records and rerunning the
process, no duplicates are written.... So we can not reproduce the fault.

I added a FEOD in pgm B, but we still get the duplicates once in a while.

The release is V7R1M0.

Both programs are RPGLE, in DFTACTGRP.

Any hints?

Thank you in advance,
Costa


------------------------------

message: 2
date: Tue, 15 May 2018 13:45:18 +0100
from: Craig Richards <craig@xxxxxxxxxxxxxxxx>
subject: Re: One Write, two records....

Costa,

Hard to say without looking at the program and tables, however it reminds
me of an issue I?ve seen in the past where a program updates a record -
changing a field which is not part of the key list it is reading by, but
another file sharing the same access path causes the program to pick up the
same record on its next read. Thus processing it twice.

If not that - is the file open for shared access? Could B occasionally be
moving the file pointer for A?

On Tue, 15 May 2018 at 13:13, Costa Marks <markscostas@xxxxxxxxx> wrote:

Hello,

The whole team I work with is facing a weird issue.

Program A loops per order and calls program B, program B is doing just a
write to a file (order lines) using the input parms from A.

Occasionally though, program B is writing 2 lines (duplicate) for some of
the order lines, not all. By deleting the records and rerunning the
process, no duplicates are written.... So we can not reproduce the fault.

I added a FEOD in pgm B, but we still get the duplicates once in a while.

The release is V7R1M0.

Both programs are RPGLE, in DFTACTGRP.

Any hints?

Thank you in advance,
Costa
--
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------------------------------

message: 3
date: Tue, 15 May 2018 08:05:43 -0500
from: Joe Pluta <joepluta@xxxxxxxxxxxxxxxxx>
subject: Re: One Write, two records....

Hi Costa!? Welcome to the world of intermittent errors.? :)

On these, the first thing to do is to identify the possible causes and
eliminate some of them.

In my mind, here are the possibilities:

1. Program A is getting called twice for the same order
2. Program A is calling program B twice for the same line
3. Program B is being called once but executing WRITE twice
4. Program B is executing WRITE once but the IBM i database is writing
two records
5. Some unknown program C is doing the same WRITE as program B

Someone might come up with more, but those are my choices.? Option 4 is
awfully far-fetched, but I include it for completeness.? Use a journal
if you suspect option 5; it will tell you if some other program or job
is writing to the same file.

Other than that, then, you have options 1, 2 and 3.? Option 1 seems
unlikely since the duplicate is for only certain lines.? So let's check
2 and 3.? The brute force method is pretty simple. Create a file with
program name, order and line number.? Every time program A calls program
B, it writes a record to that file. Every time program B writes a record
to the order file it also writes a record to the work file.

The next time the duplicate occurs, interrogate the file.? Either you'll
see program A calling program B twice with the same order and line, or
you'll see program A calling program B once and program B writing the
record twice.? That will identify which part of the business logic needs
to be debugged more thoroughly.

I know it's pretty basic stuff, but that's what I do.? A lot.? So I've
gotten pretty good at it.? :)

Hello,

The whole team I work with is facing a weird issue.

Program A loops per order and calls program B, program B is doing just a
write to a file (order lines) using the input parms from A.

Occasionally though, program B is writing 2 lines (duplicate) for some of
the order lines, not all. By deleting the records and rerunning the
process, no duplicates are written.... So we can not reproduce the fault.

I added a FEOD in pgm B, but we still get the duplicates once in a while.

The release is V7R1M0.

Both programs are RPGLE, in DFTACTGRP.

Any hints?

Thank you in advance,
Costa

------------------------------

message: 4
date: Tue, 15 May 2018 08:05:31 -0500
from: Richard Reeve <rjrjr64@xxxxxxxxx>
subject: Re: One Write, two records....

Triggers?

On Tue, May 15, 2018 at 7:45 AM, Craig Richards <craig@xxxxxxxxxxxxxxxx>
wrote:

Costa,

Hard to say without looking at the program and tables, however it reminds
me of an issue I?ve seen in the past where a program updates a record -
changing a field which is not part of the key list it is reading by, but
another file sharing the same access path causes the program to pick up the
same record on its next read. Thus processing it twice.

If not that - is the file open for shared access? Could B occasionally be
moving the file pointer for A?

On Tue, 15 May 2018 at 13:13, Costa Marks <markscostas@xxxxxxxxx> wrote:

Hello,

The whole team I work with is facing a weird issue.

Program A loops per order and calls program B, program B is doing just a
write to a file (order lines) using the input parms from A.

Occasionally though, program B is writing 2 lines (duplicate) for some of
the order lines, not all. By deleting the records and rerunning the
process, no duplicates are written.... So we can not reproduce the fault.

I added a FEOD in pgm B, but we still get the duplicates once in a while.

The release is V7R1M0.

Both programs are RPGLE, in DFTACTGRP.

Any hints?

Thank you in advance,
Costa
--
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--
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