Problem 1679

Created attachment 284 [details]
Log file for clean run - from Geant4 9.5-patch02

Added log file output from clean run with Geant4 9.5 (from Thomas and Lorenzo)

Additional information from Thomas, replying to questions:

> Could you provide a stack trace of your program when the Exception is called ?  ( Running in gdb should give you this quickly. )

I added the stacktrace at the bottom. The last stack which is within CMSSW is #16 (Geant4ePropagator::propagateGeneric).

> Are you able to reproduce the problem with the debug installation of Geant4 ?

Do you mean a specific debug compile of G4? I am not sure if this can be used from within CMSSW. But I can give it a try using only the G4 example and see if something shows up.

> How long does it take for the program to crash ?
It is hard to say. The startup takes a couple of seconds, but after that, the crash happens quite fast ( < 1s ). I counted the number of successful propagations at is it 2. The crash happens on the third.

Created attachment 285 [details]
Log file showing warnings - from Geant4 9.6-patch3

Log file using Geant4 9.6 patch 03.  Shows warnings, but no crash.

Created attachment 286 [details]
Stack trace of crash for run with Geant4 9.6 patch 02

Cleaned up stack trace (without the full AFS paths), showing the functions called before the crash.

diff -rupN geant4.10.00.p02.orig/source/geometry/navigation/src/G4Navigator.cc geant4.10.00.p02/source/geometry/navigation/src/G4Navigator.cc
--- geant4.10.00.p02.orig/source/geometry/navigation/src/G4Navigator.cc 2014-09-05 14:46:30.000000000 +0200
+++ geant4.10.00.p02/source/geometry/navigation/src/G4Navigator.cc 2014-09-05 15:37:33.000000000 +0200
@@ -1266,6 +1266,28 @@ void G4Navigator::SetupHierarchy()
}
}
+G4ThreeVector NavigateDaughtersForNormal(const G4LogicalVolume* v, const G4ThreeVector& point){
+ G4ThreeVector ExitNormal(0.,0.,0.);
+ for (int i = 0; i < v->GetNoDaughters(); ++i){
+ const G4VPhysicalVolume* cur_phys = v->GetDaughter(i);
+ const G4LogicalVolume* cur_logi = cur_phys->GetLogicalVolume();
+ G4AffineTransform transform = G4AffineTransform(cur_phys->GetRotation(), cur_phys->GetTranslation()).Invert();
+ G4ThreeVector daughterPointOwnLocal=transform.TransformPoint( point );
+ if (cur_logi->GetNoDaughters()>0){
+ ExitNormal = NavigateDaughtersForNormal(cur_logi, daughterPointOwnLocal);
+ if( std::fabs(ExitNormal.mag2()-1.0 ) < CLHEP::perMillion)
+ return ExitNormal;
+ }
+ }
+
+ G4VSolid* solid = v->GetSolid();
+ ExitNormal= -(solid->SurfaceNormal(point));
+ if( std::fabs(ExitNormal.mag2()-1.0 ) < CLHEP::perMillion )
+ return ExitNormal;
+ return ExitNormal;
+
+}
+
// ********************************************************************
// GetLocalExitNormal
//
@@ -1392,18 +1414,21 @@ G4ThreeVector G4Navigator::GetLocalExitN
{
G4VSolid* daughterSolid =fHistory.GetTopVolume()->GetLogicalVolume()
->GetSolid();
- ExitNormal= -(daughterSolid->SurfaceNormal(fLastLocatedPointLocal));
+ ExitNormal= NavigateDaughtersForNormal(fHistory.GetTopVolume()->GetLogicalVolume(), fLastLocatedPointLocal);
if( std::fabs(ExitNormal.mag2()-1.0 ) > CLHEP::perMillion )
{
G4ExceptionDescription desc;
desc << " Parameters of solid: " << *daughterSolid
<< " Point for surface = " << fLastLocatedPointLocal << std::endl;
G4Exception("G4Navigator::GetLocalExitNormal()",
- "GeomNav0003", FatalException, desc,
+ "GeomNav0003", JustWarning, desc,
"Surface Normal returned by Solid is not a Unit Vector." );
- }
- fCalculatedExitNormal= true;
- *valid = true;
+ fCalculatedExitNormal= false;
+ *valid = false;
+ } else {
+ fCalculatedExitNormal=true;
+ *valid = true;
+ }
}
else
{
@@ -1417,10 +1442,10 @@ G4ThreeVector G4Navigator::GetLocalExitN
{
*valid = false;
fCalculatedExitNormal= false;
- G4ExceptionDescription message;
- message << "Function called when *NOT* at a Boundary." << G4endl;
- G4Exception("G4Navigator::GetLocalExitNormal()",
- "GeomNav0003", JustWarning, message);
+ //G4ExceptionDescription message;
+ //message << "Function called when *NOT* at a Boundary." << G4endl;
+ //G4Exception("G4Navigator::GetLocalExitNormal()",
+ // "GeomNav0003", JustWarning, message);
}
}
}

Hi John,

in previous comment I have copied the patch proposed by Piergiulio Lenzi.

Alternatively the patch can be accessed at url:
https://github.com/lenzip/cmssw/blob/geant4e_test_giulio/TrackPropagation/Geant4e/test/geant4.10.p2_exitNormal.patch 

Cheers,
Vladimir

Created attachment 288 [details]
Analysisi of the problem and possible patch

Comment on attachment 288 [details]
Analysisi of the problem and possible patch

Hi,
this presentation contains a description of the problem and the analysis of the cause.
Cheers
Giulio

I have identified missing functionality in G4ErrorPropagationNavigator which is responsible for errors similar to the ones reported below.

In the simpler case of the error propagation example, patches in this class and in G4Navigator now give reliable results.

I have shared the improved versions of these files with those reporting the issue.

Once it is checked that the same corrections also fix the issue for the CMS use case we can mark this as resolved.

Created attachment 296 [details]
Draft patch file for G4Navigator and G4ErrorPropagationNavigator classes

Proposed corrections in tar format file.

Identified an issue in G4ErrorPropagationNavigator::ComputeStep: it calls G4Navigator::ComputeSafety, which has a side effect regarding the location.

Created a revised version of G4ErrorPropagationNavigator which addresses this.