Memory management with ROOT

Hello experts,

I am trying to fit over 100k TH1D with convoluted Landau distributions but my macro will stop working and exit root automatically after fitting about 380 histograms. I am running ROOT 6.08/00 on my own laptop (Memory 8 GB 1600 MHz DDR3). While my laptop is probably not a very powerful machine, I am wondering if there is any problem with my code (attached below).

I tried to be very careful about the memory management, for example, I reset the smart pointers when they are done even before it goes out of the scope. I also deleted all the raw pointers when they are done. Therefore I am not sure what was causing the memory issue. It will be nice if you could take a look at the following macro. Sorry for the long code, I tried to only keep the main part already.

void FitnMIPhisto(TH1D* fitThis);
#define nMipsMax 4       // what is the maximum number of MIPs you want to consider?
TF1* MipPeak[nMipsMax];  
Double_t myfunc(Double_t* x, Double_t* param);  // Fit Function used by Minuit

void AnalyzeThreeDhistoLite(TString infilename="Histos.root", TString mOutputFileName = "Fit_test"){
//Histos.root contains a lot of TH3D. This macro takes the TH3D, project it to different bins and get a TH1D, then the TH1D will be fitted by the FitnMIPhisto(TH1D* fitThis) method.
    double pi=TMath::Pi();
    //Create a title page for the PDF
    unique_ptr<TCanvas> TitlePage(new TCanvas("Title","Title",1400,1000));
    TPaveText tptitle(0.1,0.1,0.8,0.8);
    TString OutputPDFName = "Analysis_"+mOutputFileName+".pdf";
    TitlePage->SaveAs(Form("%s%s",OutputPDFName.Data(),"("));//cannot .reset() for now because it will be saved again at the end
    double centpercent[]={80,70,60,50,40,30,20,10,5,0};
    int vzrange[]={-40,-35,-30,-25,-20,-15,-10,-5,0,5,10,15,20,25,30,35,40};
    for(int cent=0;cent<1;cent++){
      for(int ew=0;ew<1;ew++){
          for(int ivz=0;ivz<1;ivz++){
            for(int ieta=0; ieta<16; ieta++){
            //----------------Create a sub title page for each eta bin---------------------
              TPaveText tptsec(0.1,0.3,0.9,0.7);
              unique_ptr<TCanvas> SectionPage(new TCanvas("ringsec","ringsec",1400,1000));
              tptsec.AddText(Form("ring %d",ieta+1));
              //--------------Open the root file and get the histograms needed------------
              unique_ptr<TFile> tf(new TFile(infilename.Data(),"READ"));
              unique_ptr<TH1F> mVz((TH1F*)tf->Get(Form("VzCent%d",cent)));
              unique_ptr<TH3F> ThreeDhist((TH3F*)tf->Get(Form("dNdphidnMIPdetaCent%dEW%dVz%d",cent,ew,ivz)));
              tf.reset();//release the memory 
              double Nevents=mVz->GetBinContent(ivz+1);
              double etaValue = ThreeDhist->GetZaxis()->GetBinCenter(ieta+1); 
              double etaBinWidth = ThreeDhist->GetZaxis()->GetBinWidth(ieta+1);
              unique_ptr<TH2F> TwoDhist((TH2F*)ThreeDhist->Project3D("yxe"));  
              TwoDhist->SetDirectory(0);//TwoDhist belongs to gDirectory which is tf.
              ThreeDhist.reset();// Now finished with ThreeDhist, free the memory
              unique_ptr<TCanvas> c1(new TCanvas(Form("dNdnMIPfitting"),Form("dNdnMIPfitting"),1400,1000));
              c1->Divide(4,3);//for 4*3=12 nMIP dis. fitting
              //--------------loop over phi bins-------------
              for(int iphi=0;iphi<12;iphi++){
                  double phiValue = TwoDhist->GetXaxis()->GetBinCenter(iphi+1); 
                  c1->cd(iphi+1)->SetLogy();//interesting, has to cd() here 

                  TH1D* dNdnMIPprojection=TwoDhist->ProjectionY(Form("Cent%dEW%dVz%dEta%dPhi%d",cent,ew,ivz,ieta,iphi),iphi+1,iphi+1,"e");//have to give it a unique name 
                  dNdnMIPprojection->SetTitle(Form("Cent=%d EW=%d ivz=%d eta=%f phi=%f",cent,ew,ivz, etaValue,phiValue));
                  dNdnMIPprojection->DrawCopy("same"); // yes, again, so it gets on top of the stats box

                  delete dNdnMIPprojection;
                  for(int i=0;i<nMipsMax;i++){
                    delete MipPeak[i];

              }//end looping over phi bins, round one [0,11]

            }//end looping over eta bins  
          }//end looping over vz
      }//end looping over ew
    }//end looping over cent 

  cout<<"finish fitting"<<endl;


// ---------------------------------- Multi-MIP fit ------------------------------------------
void FitnMIPhisto(TH1D* fitThis){

  double SingleMipPeakStartingValue = 1.0;  // where is the 1-mip peak?
  double FitRangeLow                = 0.75;  //  low edge of range along the x-axis
  double FitRangeHigh               = 8.0;  // high edge of range along the x-axis

  // (1)  ======================  Set Up the functions ===============================
  double xlo = fitThis->GetXaxis()->GetXmin();
  double xhi = 4.0*fitThis->GetXaxis()->GetXmax();
  TF1 func("MultiMipFit",myfunc,xlo,xhi,nMipsMax+2);
  // ---------------- here are the individual functions corresponding to 1,2,3,4... MIPs.  func uses them...
  MipPeak[0] = new TF1("1MIP","TMath::Landau(x,[0],[1],1)",xlo,xhi);
  for (Int_t nMIP=2; nMIP<=nMipsMax; nMIP++){
    TF1Convolution* c = new TF1Convolution(MipPeak[nMIP-2],MipPeak[0],xlo,xhi,true);
    MipPeak[nMIP-1] = new TF1(Form("%dMIPs",nMIP),c,xlo,xhi,2*nMIP);

  // (2) ======================= Set up the fit ======================================
  for (Int_t nmip=0; nmip<nMipsMax; nmip++){

  // (3) ======================= Do the fit ============================================

// ------------------------------- here is the fitting function -----------------------------------
Double_t myfunc(Double_t* x, Double_t* param){
  // parameters 0...(nMipsMax-1) are the weights of the N-MIP peaks
  // and the last two parameters, index nMipsMax and nMipsMax+1, are single-MIP MPV and WID/MPV, respectively
  Double_t ADC = x[0];
  Double_t SingleMipMPV = param[nMipsMax];
  Double_t WID = SingleMipMPV*param[nMipsMax+1];
  Double_t fitval=0.0;
  for (Int_t nMip=0; nMip<nMipsMax; nMip++){
    Double_t Weight = abs(param[nMip]);
    for (Int_t imip=0; imip<2*(nMip+1); imip+=2){
    fitval += Weight*(*MipPeak[nMip])(ADC);
  return fitval;
// -------------------------------------------------------------------------------------------------

I was running it without compilation.


_ROOT Version: ROOT 6.08/00
Platform: Not Provided
Compiler: Not Provided

There is probably a memory leak. Maybe you need to delete the histogram that you copy when calling DrawCopy or you have some leaks in the FitnMIPhisto function. I would anyway try running your code with valgrind to check for memory leaks


Hi Lorenzo,

Thanks a lot for your reply! It turned out that there was some memory leaking issue in the ROOT version that I was using (6.08). After upgrading to ROOT 6.22, the problem was solved.


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