Correct a bug because of adding particles to Geant4 (fMC is null)

[kgertsenberger]

The exception occurs when a user adds new particles to Geant4 to transport

Geant 4 calls AddParticles() function (FairMCApplication class) in own constructor but fMC pointer is initialized later in FairRunSim (fApp->InitMC).
fMC pointer (which is 0x00 in the case) was replaced by TVirtualMC::GetMC in FairMCApplication::AddParticles(), and some cosmetic modifications were made to simplify reading the function.

[fuhlig1]

Hi @kgertsenberger,

which version of Geant4 do you use? I am asking because I haven't seen the problem so far.

[kgertsenberger]

Good Day.
We use Geant4 10..2.1 version.
But the error occurs only when a user adds new particles via FairRunSim::AddParticle function. We add New particles in our generator LAQGSM. The genarators integrated in FaiRoot do not add own particles manually.

[fuhlig1]

We use Geant4 10..2.1 version. But the error occurs only when a user adds new particles via FairRunSim::AddParticle function. We add New particles in our generator LAQGSM. The genarators integrated in FaiRoot do not add own particles manually.

I also have some generator adding new particles. What is the behaviour when using the old code? Is it code simply crashing or are the particles not added to Geant4?

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[kgertsenberger]

We manually add some new particles in our LAQGSMGenerator class via
FairRunSim::Instance()->AddNewParticle(...)
So, if there are new particles, FairRunSim::SetMCConfig function contains he following code:

...
gROOT->LoadMacro(ConfigMacro.Data()); -> g4config.C
gROOT->ProcessLine("Config()");

gROOT->LoadMacro(cuts);
gROOT->ProcessLine("SetCuts()");

fApp->InitMC(ConfigMacro.Data(), cuts.Data());

g4config.C calls TGeant4 constructor which calls FairMCApplication::AddPatrticles with fMC zero pointer, because fMC will be initialized in fApp->InitMC.

The following exception happens on the line "fMC->DefineParticle(particle->GetPDG(), ..."

Adding SpecialPhysicsList stepLimiter+specialCuts
[INFO   ] Add Particle: LP with PDG 1010010020
LP           // const TString& name 
3           // TMCParticleType mcType 
2.05388             // Double_t mass   
1           // Double_t charge 
2.6e-10        // Double_t lifetime  
hadron          // const TString& pType, 
0         // Double_t width   
0         // Int_t iSpin  
0         // Int_t iParity 
0      // Int_t iConjugation  
0       // Int_t iIsospin   
0       // Int_t iIsospinZ    
0       // Int_t gParity    
0         // Int_t lepton  
0         // Int_t baryon   
0         // Bool_t stable   

 ** Break ** segmentation violation
===========================================================
There was a crash (kSigSegmentationViolation).
This is the entire stack trace of all threads:
===========================================================
#0  0x00007f154e1963b7 in __GI___waitpid (pid=11900, stat_loc=stat_loc
entry=0x7ffebd4ad4f8, options=options
entry=0) at ../sysdeps/unix/sysv/linux/waitpid.c:30
#1  0x00007f154e107f17 in do_system (line=<optimized out>) at ../sysdeps/posix/system.c:149
#2  0x00007f154e897796 in TUnixSystem::Exec (this=0x55ac9d368740, shellcmd=0x55aca4606210 "/opt/fairsoft/install/share/root/etc/gdb-backtrace.sh 11805 1>&2") at /opt/fairsoft/tools/root/core/unix/src/TUnixSystem.cxx:2118
#3  0x00007f154e898061 in TUnixSystem::StackTrace (this=0x55ac9d368740) at /opt/fairsoft/tools/root/core/unix/src/TUnixSystem.cxx:2412
#4  0x00007f154e89bc88 in TUnixSystem::DispatchSignals (this=0x55ac9d368740, sig=kSigSegmentationViolation) at /opt/fairsoft/tools/root/core/unix/src/TUnixSystem.cxx:3643
#5  0x00007f154e893556 in SigHandler (sig=kSigSegmentationViolation) at /opt/fairsoft/tools/root/core/unix/src/TUnixSystem.cxx:408
#6  0x00007f154e89bbdb in sighandler (sig=11) at /opt/fairsoft/tools/root/core/unix/src/TUnixSystem.cxx:3620
#7  0x00007f154e88c578 in textinput::TerminalConfigUnix::HandleSignal (this=0x7f154ea306e0 <textinput::TerminalConfigUnix::Get()::s>, signum=11) at /opt/fairsoft/tools/root/core/textinput/src/textinput/TerminalConfigUnix.cpp:100
#8  0x00007f154e88c29a in (anonymous namespace)::TerminalConfigUnix__handleSignal (signum=11) at /opt/fairsoft/tools/root/core/textinput/src/textinput/TerminalConfigUnix.cpp:36
#9  <signal handler called>
#10 0x00007f1545127011 in FairMCApplication::AddParticles (this=0x55aca3573b50) at /opt/fairroot/base/sim/FairMCApplication.cxx:1238
#11 0x00007f152295f513 in TG4UserParticlesPhysics::ConstructParticle (this=0x55aca44e96b0) at /opt/fairsoft/transport/geant4_vmc/source/physics_list/src/TG4UserParticlesPhysics.cxx:79
#12 0x00007f15283050e6 in G4VModularPhysicsList::ConstructParticle (this=0x55aca44dfd40) at /opt/fairsoft/transport/geant4/source/run/src/G4VModularPhysicsList.cc:115
#13 0x00007f1522945de4 in TG4ComposedPhysicsList::ConstructParticle (this=0x55aca35cc6a0) at /opt/fairsoft/transport/geant4_vmc/source/physics_list/src/TG4ComposedPhysicsList.cxx:77
#14 0x00007f15282f81bf in G4RunManagerKernel::SetupPhysics (this=0x55aca41f1c50) at /opt/fairsoft/transport/geant4/source/run/src/G4RunManagerKernel.cc:480
#15 0x00007f15282f8000 in G4RunManagerKernel::SetPhysics (this=0x55aca41f1c50, uPhys=0x55aca35cc6a0) at /opt/fairsoft/transport/geant4/source/run/src/G4RunManagerKernel.cc:455
#16 0x00007f15282eaae9 in G4RunManager::SetUserInitialization (this=0x55aca386b590, userInit=0x55aca35cc6a0) at /opt/fairsoft/transport/geant4/source/run/src/G4RunManager.cc:841
#17 0x00007f152296d7f1 in TG4RunManager::ConfigureRunManager (this=0x55aca3b7f6b0) at /opt/fairsoft/transport/geant4_vmc/source/run/src/TG4RunManager.cxx:238
#18 0x00007f152296cffe in TG4RunManager::TG4RunManager (this=0x55aca3b7f6b0, runConfiguration=0x55aca4037e00, argc=0, argv=0x0) at /opt/fairsoft/transport/geant4_vmc/source/run/src/TG4RunManager.cxx:102
#19 0x00007f1522970b93 in TGeant4::TGeant4 (this=0x55aca3b594f0, name=0x7f1541d981c9 "TGeant4", title=0x7f1541d981d1 "The Geant4 Monte Carlo", configuration=0x55aca4037e00, argc=0, argv=0x0) at /opt/fairsoft/transport/geant4_vmc/source/run/src/TGeant4.cxx:231
#36 0x00007f154b2af31c in cling::IncrementalExecutor::executeWrapper (returnValue=0x55aca4037e00, function=..., this=0x55ac9d4247b0) at /opt/fairsoft/tools/root/interpreter/cling/lib/Interpreter/IncrementalExecutor.h:197
#37 cling::Interpreter::RunFunction (this=<optimized out>, FD=<optimized out>, res=0x55aca4037e00) at /opt/fairsoft/tools/root/interpreter/cling/lib/Interpreter/Interpreter.cpp:916
#38 0x00007f154b2af5bd in cling::Interpreter::EvaluateInternal (this=0x55ac9d3ca900, input="Config()", CO=..., V=V
entry=0x7ffebd4b0950, T=T
entry=0x0, wrapPoint=<optimized out>, wrapPoint
entry=0) at /opt/fairsoft/tools/root/interpreter/cling/include/cling/Interpreter/Transaction.h:476
#39 0x00007f154b2af9c2 in cling::Interpreter::process (this=<optimized out>, input="Config()", V=V
entry=0x7ffebd4b0950, T=T
entry=0x0, disableValuePrinting=disableValuePrinting
entry=false) at /opt/fairsoft/tools/root/interpreter/cling/lib/Interpreter/Interpreter.cpp:621
#40 0x00007f154b33e22f in cling::MetaProcessor::process (this=0x55ac9dc2cb30, input_text=<optimized out>, compRes=
0x7ffebd4b090c: cling::Interpreter::kSuccess, result=0x7ffebd4b0950, disableValuePrinting=<optimized out>) at /opt/fairsoft/tools/root/interpreter/cling/lib/MetaProcessor/MetaProcessor.cpp:341
#41 0x00007f154b1ac664 in HandleInterpreterException (metaProcessor=0x55ac9dc2cb30, input_line=0x7ffebd4b0989 "Config()", compRes=
0x7ffebd4b090c: cling::Interpreter::kSuccess, result=0x7ffebd4b0950) at /opt/fairsoft/tools/root/core/metacling/src/TCling.cxx:1887
#42 0x00007f154b1ad341 in TCling::ProcessLine (this=0x55ac9d3be260, line=0x7ffebd4b0e69 "Config()", error=0x0) at /opt/fairsoft/tools/root/core/metacling/src/TCling.cxx:2051
#43 0x00007f154e736cdd in TApplication::ProcessLine (this=0x55ac9d3b4170, line=0x7ffebd4b0e69 "Config()", sync=false, err=0x0) at /opt/fairsoft/tools/root/core/base/src/TApplication.cxx:1001
#44 0x00007f154e69b56e in TROOT::ProcessLine (this=0x7f154ea04180 <ROOT::Internal::GetROOT1()::alloc>, line=0x7f15451875bb "Config()", error=0x0) at /opt/fairsoft/tools/root/core/base/src/TROOT.cxx:2219
#45 0x00007f1545113f57 in FairRunSim::SetMCConfig (this=0x55aca2e78710) at /opt/fairroot/base/steer/FairRunSim.cxx:408
#46 0x00007f1545116541 in FairRunSim::Init (this=0x55aca2e78710) at /opt/fairroot/base/steer/FairRunSim.cxx:243