Problem 2137

Dear Sandsik Yoon,

Thank you for your report.

I have looked at the slides in which you describe the problem.

I find it difficult though to use the long output of the debugger in its current form. Could you please upload each text output file as a simple text file(s).

That will allow us to use any text editor to view this file instead of using a PDF viewer.

Best regards,
John Apostolakis

Created attachment 549 [details]
This input file for gdb creates "watch.txt" file.

Created attachment 550 [details]
This file shows the changes of values of two variables: CurrentA_PointVelocity and CurrentB_PointVelocity.

The value of CurrentA_PointVelocity at $87=87 and the value of CurrentB_PointVelocity at $98=98 are the same, which leads to the hstep = 0 error.

Created attachment 551 [details]
This input file for gdb creates "detector.txt" file.

Created attachment 552 [details]
This file shows the information of detectors when the errors occurred.

I do not think this file may be useful, but I have attached it to describe that hstep = 0 errors occurred at a variety of detectors.

(In reply to John Apostolakis from comment #1)
> Dear Sandsik Yoon,
> 
> Thank you for your report.
> 
> I have looked at the slides in which you describe the problem.
> 
> I find it difficult though to use the long output of the debugger in its
> current form. Could you please upload each text output file as a simple text
> file(s).
> 
> That will allow us to use any text editor to view this file instead of using
> a PDF viewer.
> 
> Best regards,
> John Apostolakis

Dear John Apostolakis, 

I have added new attachments : "input_watch.in", "watch.txt", "input_detector.in", and "detector.txt"
I hope "input_watch.in" and "watch.txt" files may be helpful. 
I think that it requires to run Belle II Software to test a patch file, so please let me know at any time if you need any further information. 

Best regards,
Sangsik Yoon

Hi Sangsik, 

Sorry for the long silence.  I have tried in the last days to understand the output of the debugger which you have posted.  To do this I processed the output of the printing of the watchpoints from the debugger in order to see the evolution of CurrentA_PointVelocity and CurrentB_PointVelocity - in particular their values of the distance along the track, the position and the momentum 3-vectors.

I attach the file which I created, to document this progress more easily by putting the values of CurrentA_PointVelocity and CurrentB_PointVelocity into columns using a script.  

I do not suggest that this identifies the problem yet, but I want to keep this to help in further investigation.

Created attachment 582 [details]
Progression of the state of CurrentA_PointVelocity and CurrentB_PointVelocity

This file with very long lines contains the current values and the changes in CurrentA_PointVelocity and CurrentB_PointVelocity, extracted from watch.txt

Created attachment 583 [details]
Script used to create comparison of values of  CurrentA,B_PointVelocity

Dear Dr. John Apostolakis,

Thank you for letting me know about the progress of this issue. As far as I remember, the line 449 in G4MultiLevelLocator.cc makes CurrentA_PointVelocity and CurrentB_PointVelocity have the same value. Please let me know if there is any further progresses or if there is anything that I need to test in the Belle II Software environment. 

Best Regards,
Sangsik Yoon

Used new code to store the intermediate points / intervals of integration within AccurateAdvance, and adding a print statement inside the error report.

Dennis Wright reran the application, and provided the new output from the errors.
I copy below the first case.

********* Zero step event #1 ****************
ERROR> Point B has gone past point A
 ** Change records: 
MLL: iters = 4
=====================================================================
  Size of individual change record:  startA : 2  endB : 5
=====================================================================
Change#  Iter          CodeLocation           Length-A (start)             Length-B (end)  
=====================================================================
      1     0    2    Initialising                         0          30.11455759098148     0                2
      2     0    3    IntersectsAF                                    24.46186452078947  
      3     1    3    IntersectsAF                                    24.45830312608917  
      4     2    3    IntersectsAF                                    24.45830136494451  
      5     3    4    IntersectsFB         24.45830136436696                             
      6     3    6   RecalculatedB                                    24.45830136436696  
[ERROR] In G4MagInt_Driver::AccurateAdvance(), GeomField1001: Proposed step is zero; hstep = 0 !  { module: Ext }

Dear Sangsik, 

Is this still an issue in Belle II ?

Best,
John

DearJohn,

    Sangsik moved to another experiment. I will ask around Belle II if they are still seeing the error.

We've added additional logging functionality to aid in diagnosing such problems.

Please let us know if it persists.