Problem 1304

Summary:	Very large number of warnings of Infinite loop from G4SubtractionSolid
Product:	Geant4	Reporter:	John Apostolakis <John.Apostolakis>
Component:	geometry/solids	Assignee:	tatiana.nikitina
Status:	RESOLVED FIXED
Severity:	normal
Priority:	P3
Version:	9.5
Hardware:	PC
OS:	Linux
URL:	https://savannah.cern.ch/bugs/?93709

Description John Apostolakis 2012-04-16 12:37:36 CEST

An ATLAS simulation job (part of MC12 AFII simulations of the calibration jet samples) was aborted on the grid due to too large stdout file. 

It contained mainly this error message: 

G4Exception : InfiniteLoop
issued by : G4SubtractionSolid::DistanceToIn(p,v) 
Illegal condition caused by solids: DisplacedSolid and G4Tubs 
This is just a warning message.
G4SubtractionSolid::Looping detected in : 
Point p=(735.7919806321661,4234.225434662997,-8.447424088051775) and 
Dir=(-0.9957317618352194,-0.09115072784067567,0.0144845879004132)

https://savannah.cern.ch/bugs/?93709

Comment 1 Gabriele Cosmo 2012-04-16 14:03:36 CEST

The error message indicates that there is likely a problem in the geometry under consideration (subtraction of shared surfaces can a source of the problem... also, consider that it is printed out every 1000 failed attempts!).
In order to debug the problem it would be useful if you provide the exact geometry setup so that we can reproduce it.

Comment 2 John Apostolakis 2012-04-17 21:07:08 CEST

To clarify:  

It is exactly the same message which appears each time - with the same point
and direction.

So the simulation is stuck at this location.

Comment 3 tatiana.nikitina 2012-08-14 08:22:03 CEST

Error was fixed in DistanceToIn(p,v) of the G4SubtractionSolid.
In case of detected loop solid returns dist, before it was retourning zero.
Still remains issue in Navigator, the loop with zero step length was not detected by Navigator in case of parallel geometries.