Histogram filling failure

ROOT
1

Hi,

I have a selector that compiles and works on my local machine. The Process function fills 340 1D histograms. However, when I run the selector on PROOF on the CAF, the selector compiles and runs, but the histograms are empty. Does anybody know how this can be?

Rasmus

2

This problem has been investigated by Jan Fiete. Here is his answer.

I guess you are using Draw and not DrawCopy. Histograms are in the output list and thus deleted once the selector terminates. I am not even sure it this is good behavior…

Rene

3

Hi again. I tried with simpler code, and it still gives an empty histogram; here is the code (it compiles locally), only the nonempty functions…

void AliTPCPositionSelector::SlaveBegin(TTree *tree)
{
fIDHist = new TH1I(“IDS”, “IDS”, 400, -1, 400);
fOutput->Add(fIDHist);
}

Bool_t AliTPCPositionSelector::Process(Long64_t entry)
{
fChain->GetTree()->GetEntry(entry);
Int_t ntracks = fESD->GetNumberOfTracks();

if (!fESD) {return kFALSE;}
// if (TPCPositionSelector::Process(entry) == kFALSE)
// {return kFALSE;}
if (!fESDfriend) return kFALSE;

fESD->SetESDfriend(fESDfriend);

ID = 0;
for (Int_t esdtrack = 0; esdtrack GetTrack(esdtrack);
AliESDfriendTrack * ftrack = (AliESDfriendTrack )fESD->GetTrack(esdtrack)
->GetFriendTrack();
AliTPCseed * trackseed = (AliTPCseed) ftrack->GetCalibObject(0);

ID = fFit.MakeID(track);
fIDHist->Fill(ID);

}

return kTRUE;
}
void AliTPCPositionSelector::Terminate()
{
TFile file(“MirrorPositions.root”,“recreate”);
fOutput->Write();
}

void AliTPCPositionSelector::Init(TTree *tree)
{
if (!tree) return;
fChain = tree;
fChain->SetBranchAddress(“ESD”,&fESD);
fChain->SetBranchAddress(“ESDfriend”,&fESDfriend);
fChain->SetCacheSize(0);
}

Thanks in advance

Rasmus