topic Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?) in Application Development and Automation Discussions

Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

pawel_jagus_b2tec — Tue, 25 Jun 2019 08:10:19 GMT

Hi,

I have been developing in ABAP for some years now but I have run into the following bug(?) just now.

There was a programming error in one of my programs which lead to a timeout. It took me some time to figure out what was wrong and in the end it was nested `LOOP AT SCREEN`. I have not found any article on that topic nor anything in the documentation.

I posted a question on Stackoverflow:

https://stackoverflow.com/questions/56748140/why-does-nested-loop-at-screen-cause-infinite-loop-recursion

Actually I wanted to approach horst.keller directly but I am unsure how to do it here.

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

Sandra_Rossi — Tue, 25 Jun 2019 08:39:31 GMT

As a side note, let me say that your question in stackoverflow is sufficiently clear and documented to directly copy & paste it into a ticket at SAP support. If you don't have access to the support (no S-user), I can open one on your behalf (SAP support is nice: I opened a ticket recently and I had a positive answer; even SAP staff opens tickets on their own if they feel SCN questions underlie bugs)

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

pawel_jagus_b2tec — Tue, 25 Jun 2019 08:46:06 GMT

Hi, Sandra, I do have an S-User but unfortunately I do not have authority to submit a ticket. If this is also interesting to you I would not mind if you create an incident by yourself by just copying & pasting what I have posted on SO.

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

Sandra_Rossi — Tue, 25 Jun 2019 09:13:18 GMT

Done (link for my own purpose : https://launchpad.support.sap.com/#/incident/pointer/002075129400003756892019).

I will update this thread as soon as I have an answer.

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

matt — Tue, 25 Jun 2019 12:08:16 GMT

A good question with interesting answers. Thanks for raising it!

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

Sandra_Rossi — Fri, 05 Jul 2019 08:29:29 GMT

Update: I got a message from SAP, they are still investigating; they have to make sure that the incorrect behavior is only limited to an endless loop, and if it's the same behavior in all other supported versions. If it's only an endless loop, in all versions, they would simply raise a runtime error.

As an example of a possible different behavior, this old thread is talking about "The loop at screen [...] lose its correct index", but doesn't mention an endless loop.

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

pawel_jagus_b2tec — Tue, 09 Jul 2019 06:34:30 GMT

Thanks for the update Sandra! I am happy that they considered it as an issue and are working on it.

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

Sandra_Rossi — Tue, 17 Sep 2019 11:28:40 GMT

For information, SAP support is still "working" on it...

Re: Nested LOOP AT SCREEN leads to an infinite loop (recursion?)

pawel_jagus_b2tec — Tue, 17 Sep 2019 12:22:56 GMT

I think there is some regression to be done by such a change, therefore the long processing time.