Problem running Geant4 + Root in multithreading

[Elia_Bottalico]

Hi,
I’m running a simulation using Geant4. To select the energy of the generated particle I’m using TH1 → GetRanom() read from a root file (using TFile.Open() to open/read it). The simulation runs smoothly when I use a single thread, but when I set the multithreading an error occurs at the begin of the simulation:

Fatal in <TClass::Init>: gInterpreter not initialized
aborting
[/Applications/root_v6.14.06/lib/libCore.so] ErrorHandler (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] Fatal(char const*, char const*, ...) (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] TClass::Init(char const*, short, std::type_info const*, TVirtualIsAProxy*, char const*, char const*, int, int, ClassInfo_t*, bool) (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] TClass::TClass(char const*, short, std::type_info const&, TVirtualIsAProxy*, char const*, char const*, int, int, bool) (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] ROOT::CreateClass(char const*, short, std::type_info const&, TVirtualIsAProxy*, char const*, char const*, int, int) (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] ROOT::Internal::TDefaultInitBehavior::CreateClass(char const*, short, std::type_info const&, TVirtualIsAProxy*, char const*, char const*, int, int) const (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] ROOT::TGenericClassInfo::GetClass() (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] TObjString::Class() (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] TObjString::CheckTObjectHashConsistency() const (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] THashTable::Add(TObject*) (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] TPluginManager::LoadHandlersFromPluginDirs(char const*) (no debug info)
[/Applications/root_v6.14.06/lib/libCore.so] TPluginManager::FindHandler(char const*, char const*) (no debug info)
[/Applications/root_v6.14.06/lib/libRIO.so] TFile::Open(char const*, char const*, char const*, int, int) (no debug info)
[/Users/eliabottalico/Documents/Geant4_simulation/B4c_build/./exampleB4c] B4PrimaryGeneratorAction::B4PrimaryGeneratorAction() (no debug info)
[/Users/eliabottalico/Documents/Geant4_simulation/B4c_build/./exampleB4c] B4cActionInitialization::Build() const (no debug info)
[/Users/eliabottalico/Documents/G4-install/lib/libG4run.dylib] G4MTRunManagerKernel::StartThread(G4WorkerThread*) (no debug info)
[/Users/eliabottalico/Documents/G4-install/lib/libG4run.dylib] void* std::__1::__thread_proxy<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, void (*)(G4WorkerThread*), G4WorkerThread*> >(void*) (no debug info)
[/usr/lib/system/libsystem_pthread.dylib] _pthread_body (no debug info)
[/usr/lib/system/libsystem_pthread.dylib] _pthread_start (no debug info)
[/usr/lib/system/libsystem_pthread.dylib] thread_start (no debug info)
Abort trap: 6

Do you have any idea about what is happening?

_ROOT Version:6.14.00
_Geant4 Version:10.6.1
Platform: MacOS Mojave - 10.14.6

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[couet]

May be that’s a question for the GEANT4 forum ?

[Elia_Bottalico]

Ok, I’ll try to move the question to GEANT4 forum. Thanks!

[Elia_Bottalico]

Just to inform people who will read this post, I solved the problem by introducing, before TFile::Open() the function ROOT::EnableThreadSafety(); In this way is possible to Mutex the “open” function and prevent threads from accessing the file at the same time.