Pull from List not fulfilled but should be

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Guillaume V asked Sep 7, '21 Guillaume V commented Sep 7, '21

Pull from List not fulfilled but should be

Hello,

On the model that I attach, at ~9000seconds, the model gets stuck due to:
A Pull From List activity doesn't fulfill its activity because it doesn't find what it is looking for.

The problem is that:
It should fulfill its activity as the query in the Pull From List is" WHERE ParentID = puller.ParentID". and both the puller and the token in the list at the time have ParentID = 1.

I have tried a lot of problem-solving techniques but I am unable to understand the reason why my pull from activity doesn't fulfill the request.

INFORMATION:

Pull From List = "Remove ParentID from PREPREP"
List = "NestsPrePrep"
Time = ~9000seconds

Screenshot =

Model = NotPullingFromListProperlyAt9000s.fsm

Software Version:

FlexSim 19.0.0

processflow list flexsim 19.0.0 pull from list process flow pull from list

1631006431670.png (146.1 KiB)

notpullingfromlistproperlyat9000s.fsm (102.6 KiB)

5 |100000

Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Answer 1 · 2021-09-07T10:33:35Z

Felix Möhlmann answered Sep 7, '21 Guillaume V commented Sep 7, '21

This happens due to a timing collision with your other check whether there are entries on the list.

The tokens there try to pull the same entry from the list. Yes, the activity is set to "Leave entries on list", but both "Pull from List" activities happen simultaneously. So one of the "check"-tokens might pull the value and before it is made available again, the pull from the token further down was unsuccessful. It then doesn't get evaluated again, because no new entry gets added to the list.

The probability of this happening increases with more tokens trying to pull at the same time, which is probably why it only happens later on in the run.

The solution is to place a zero-second delay (the devs call these "Breathe", so I stick with that) after the wait for event activity. Now, the token further down gets to try to pull the value first, before the "check"-tokens get to go.

(Or you change the setting in the wait for event to "Increase to or through value" and skip the pull from list, as you then know that there are entries on the list)

notpullingfromlistproperlyat9000s_fm.fsm

1631010593529.png (41.5 KiB)

notpullingfromlistproperlyat9000s-fm.fsm (103.9 KiB)

· 1

5 |100000

Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Guillaume V commented · Sep 07, 2021 at 10:51 AM

Thanks, @Felix Möhlmann

I didn't know this concept. Thank you for your clear explanation.

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