Problem reading tree via event class on a branch

ROOT
1

Hello,

I have a tree I wrote to disk like this

        detectorTree = new TTree ( "Detectors","Detector Tree" );
        recordedEvent = new BETAEvent();
        detectorTree->Branch ( "aBetaEvent","BETAEvent",&recordedEvent );
// .. adding data and filling etc...

I can open up a TBrowser and everything looks fine (the data is there)

However when I try to read in the tree to do some analysis like this :

gROOT->ProcessLine(".L BETAEvent.C");
BETAEvent * event = new BETAEvent();
TFile * f = new TFile("data/beta.run.10825.root");
TTree *t = (TTree*)f->Get("Detectors");
t->SetBranchAddress("aBetaEvent", &event);
Int_t nevent = t->GetEntries();
for (int i=0;i<nevent;i++) 
    {
gDebug=2;  
 t->GetEvent(i); // <- Crashes here
}

I get the infamous *** Break *** segmentation violation

Any ideas why?

Thanks in advance!

-Whitney

2

Hi,

You must compile the user object/class. Use gROOT->ProcessLine(".L BETAEvent.C+");

Cheers,
Philippe

3

Thanks for your response.

I made said changes and now it crashes at setting the branch address! However, I noticed after executing the script and getting :

 *** Break *** segmentation violation

if I just run the script again ( .x EventDisplay.cxx)
without leaving the interpreter it appears to run fine!???

Any ideas what to do to fix this?

Thanks

4

Hi,

Can you provide a complete running example showing the issue?

Philippe.

5

In the tar file you will find the output of two sessions one without gDebug and one with gDebug=2.

After executing the script again (up arrow then return) it runs smoothly (as can be seen in the output)

I include the script and the event class code as well. There is also a root file which contains a tree with a few events.

Thanks!
buggy_event.tar (730 KB)

6

Hi,

The problem, as shown by valgrind:root [0] .x EventDisplay.cxx ==11080== Conditional jump or move depends on uninitialised value(s) ==11080== at 0x7BAE7A0: BETAEvent::~BETAEvent() (BETAEvent.C:18) ==11080== by 0x4E9F582: TClass::BuildRealData(void*, bool) (TClass.cxx:1333) is a missing initialization in the constructor of BETAEvent. Use:[code] BETAEvent::BETAEvent() : fChain(0)
{
// if parameter tree is not specified (or zero), connect the file
// used to generate this class and read the Tree.

}[/code]

Cheers,
Philippe

7

SOLVED. After making the correction to BETAEvent it now works properly.

Thanks for your help!

Cheers,
Whit