gBenchmark in g++ compiled code: segmentation violation

[kimd99]

Hello,
I am trying to use gBenchmark to compare real and CPU time of a macro in interpreted mode versus compiled mode. I have created a standalone application to be able to compile the code with g++, version 9.1. To reproduce the error, here is a simple example:

#include "TApplication.h"
#include "TH1F.h"
#include "TBenchmark.h"

void  ExampleMacro_GUI(){
gBenchmark->Start("example");
TH1F* h=new TH1F("h", "test histogram", 100,-5.,5.);
h->FillRandom("gaus",1E4);
h->Draw("H");
h->Draw("E,P,SAME");
gBenchmark->Show("example");
}

void StandaloneApplication(int argc, char** argv) {
  ExampleMacro_GUI();
}


int main(int argc, char** argv) {
   TApplication app("ROOT Application", &argc, argv);
   StandaloneApplication(app.Argc(), app.Argv());
   app.Run();
   
   return 0;
}

Using gBenchmark causes a segmentation violation:

There was a crash.
This is the entire stack trace of all threads:
===========================================================
#0  0x00007f5717f99387 in __GI___waitpid (pid=20199, stat_loc=stat_loc
entry=0x7ffd63e2f608, options=options
entry=0) at ../sysdeps/unix/sysv/linux/waitpid.c:30
#1  0x00007f5717f0ad57 in do_system (line=<optimized out>) at ../sysdeps/posix/system.c:167
#2  0x00007f57189eecf0 in TUnixSystem::Exec (shellcmd=<optimized out>, this=0x55fd6b5b0b80) at /home/kimdamiani/Products/root-6.18.04/core/unix/src/TUnixSystem.cxx:2106
#3  TUnixSystem::StackTrace (this=0x55fd6b5b0b80) at /home/kimdamiani/Products/root-6.18.04/core/unix/src/TUnixSystem.cxx:2400
#4  0x00007f57189f1754 in TUnixSystem::DispatchSignals (this=0x55fd6b5b0b80, sig=kSigSegmentationViolation) at /home/kimdamiani/Products/root-6.18.04/core/unix/src/TUnixSystem.cxx:3631
#5  <signal handler called>
#6  0x000055fd6a6a81ee in ExampleMacro_GUI() ()
#7  0x000055fd6a6a82fe in StandaloneApplication(int, char**) ()
#8  0x000055fd6a6a8384 in main ()
===========================================================


The lines below might hint at the cause of the crash.
You may get help by asking at the ROOT forum http://root.cern.ch/forum
Only if you are really convinced it is a bug in ROOT then please submit a
report at http://root.cern.ch/bugs Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.
===========================================================
#6  0x000055fd6a6a81ee in ExampleMacro_GUI() ()
#7  0x000055fd6a6a82fe in StandaloneApplication(int, char**) ()
#8  0x000055fd6a6a8384 in main ()

Is it because I am compiling with g++ instead of ACLiC?
Any help would be greatly appreciated.

_ROOT Version: 6.18/04
_Platform: Ubuntu 19.04 x86_64

[OSchaile]

Hi,
seems that TApplication does not initialize gBenchmark.
I ran your example with gdb and find gBenchmark == NULL
Using TRint instead works:

int main(int argc, char** argv) {
  TRint *theApp = new TRint("App", &argc, argv);
 //   TApplication app("ROOT Application", &argc, argv);
   StandaloneApplication(argc, argv);
   theApp->Run(kFALSE);
   
   return 0;

The following helps also:

 gBenchmark = new TBenchmark();
 StandaloneApplication(argc, argv);

Running ACliC in a root session has gBenchmark initialized

Cheers
Otto

[Wile_E_Coyote]

   TApplication app("ROOT Application", &argc, argv);
   gBenchmark = new TBenchmark();

[kimd99]

Thank you both so much for your quick and clear answers!