What causes the random errors in the attached model?

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Tee Hiett asked Jul 18, '20 Tee Hiett commented Aug 18, '20

What causes the random errors in the attached model?

I am getting a series of five exception error statements occurring randomly in this model. as shown in the graphic, the error occurred once for each first three scenarios. Sometimes it occurs only in one scenario and sometimes it does not occur at all. The messages are shown in the Exceptions-error graphic. when I examine the length of stay for each of the 3 occurrences shown, the length of stay is zero.

Any help would be appreciated.

Thanks,

Tee

Software Version:

FlexSim 20.1.0

flexsim 20.1.0 exception error random errors

occurrences-of-exception-error.jpg (96.6 KiB)

exception-error.jpg (158.3 KiB)

master-clinic-model-14.fsm (3.3 MiB)

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tannerp commented · Jul 20, 2020 at 09:42 PM

@tee.hiett,

I took a look at your model and found a couple issues that may be causing the errors you described. The first I found was that the tokens at the "Get NP- Exam-Consult" activity are acquiring a staff resource and then the NP is being released by the parent token. It seems to be throwing things off so that you get the "Bad Task Executer reference" error in the System Console. Maybe it would be better to release the NP in the sub-flow using the Child Token rather than relying on the Parent Token.

Additionally, there are a few errors that occur in the Global Lists. I can't pinpoint what's causing them, but these are the "onFulfill" errors that occur. I would think that resolving some of these errors might prevent problems in the Experimenter results.

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errors-list-tee.png (24.5 KiB)

Tee Hiett tannerp commented · Jul 27, 2020 at 03:42 PM

Master Clinic Model _18a.fsm

Good Morning @tanner.p

I have modified the Patient Flow chart and I am still getting the same exception messages. When I run the experimenter for 128 replications, I may get 0, 5, 15 or 18 replications where the Avg LOS by Provider is 0.

When I click on the View Results button in the Simulation Experiment Control and examine the Dashboard Statistics for the experiment, all those replications where the LOS is zero, have no value in the charts. When I examine those same replications for the Statistics Tables tab, there are no data in those tables but all of the other replications do have data. So I am assuming those replications with the exception message are not included in any averages.

I have gone about as far as I can go trying to identify any characteristics which would help solve the problem. So I'm turning to the experts for an help.

This master model has almost all the activities we need in any of the 40 odd clinics in this Kirklin Clinic of UAB. I would like to get this problem solved because as soon as we get FlexSim 2020 on the server at the clinic, I plan to use this model to help the members of the performance improvement team use it as a master model for developing models in the clinics.

Thanks for the help.

Tee

PS: I just noticed that the prior version I sent had an subset number error that I fixed

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master-clinic-model-18a.fsm (1.2 MiB)

tannerp Tee Hiett commented · Jul 27, 2020 at 05:36 PM

Hi @tee.hiett,

I ran the experimenter in your model a few times and was unable to find any replications with the Avg LOS by Provider as 0. Here's a screenshot of what the data looked like for my trials.

Am I looking at the wrong thing? Or maybe I misunderstood the question. Also, is it possible that the Avg LOS by Provider could be 0? Or is that an absolute impossibility based on how your model is set up?

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replications-plot.png (18.2 KiB)

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Answer 1 · 2020-08-17T19:47:57Z

Jordan Johnson answered Aug 17, '20 Tee Hiett commented Aug 18, '20

Hi Tee,

Somehow, there are activities outside of a process flow. If you run this script, you can find them. You can also uncomment the line in the script to delete them:

Array badActivities = [];
forobjectlayerunder(model()) {
	if (isclasstype(a, "ProcessFlow::ProcessBlock")) {
		badActivities.push(a);
	}
}

for (int i = 1; i <= badActivities.length; i++) {
	// uncomment to delete them
        // leave commented to see the list of bad activities
	// badActivities[i].destroy();
}

return badActivities;

I'm not sure how this happened, and why it doesn't create an issue sooner. But removing these activities may fix your issue.

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Tee Hiett commented · Aug 18, 2020 at 10:11 PM

Thanks, @jordan.johnson. That script got rid of 4 errors. I ran 7 experiments for 256 replications each and got only 1 replication with an average LOS of zero.. Interestingly enough, each one of those errors had the number 73.

Array[4]: /Acquire WR73, /Finish CheckOut73, /Record Notes73, /Remove Patient73. Does that raise any questions in your mind?

Thanks for your help,

Tee

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Answer 2 · 2020-07-28T17:08:15Z

Jordan Johnson answered Jul 28, '20 Tee Hiett edited Aug 15, '20

My guess is that this bug is related to the "Restore original state after each replication" checkbox. With that box unchecked, I was able to run the experiment 5 times in a row, and not see any issues. I would try that. I'll be sure to add this bug to the dev list.

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Tee Hiett commented · Jul 30, 2020 at 09:47 PM

@jordan.johnson Unchecking the "Restore original state after each replication" doesn't seem to solve the problem. Any other suggestions?

Thanks for reporting this to the dev list.

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Jordan Johnson ♦♦ Tee Hiett commented · Jul 30, 2020 at 09:54 PM

Hmm. I was unable to replicate the issue without that box checked. I can keep trying, though. But can you confirm that the issue occurs in version 20.1.3? This question is tagged for 20.1.0, and I just want to be sure that the issue exists for you on the latest bug fix release.

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Tee Hiett Jordan Johnson ♦♦ commented · Jul 31, 2020 at 06:25 PM

Version 20.1.3 did not resolve the problem.

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