Re: [ROOT] ROOT 20 times slower

From: Kalen Martens (fmartens@physics.utoronto.ca)
Date: Wed Jan 23 2002 - 03:48:44 MET


Hi Again,

I've narrowed down the problem a little more. 

Yes, my PATH and LD_LIBRARY_PATH variables point to the new version. I
never used the TTree::MakeCode in 3.02/07 to create my analysis code, but
it does appear when I use it in 3.02/07.

Below is the short bit of code from my h3333.C that generates a
segmentation fault in 3.02/07 when it is first run. The interpreter
recovers, and when it is run again, it takes a long time to go through the
50K events in the root file. The ROOT version 3.01/06 has no problem
running this.

(I loaded libPhysics.so at the beginning of the code.)

//     This is the loop skeleton

   TH1F *hmj = new TH1F("hmj", "muon-jet separation", 100, 0, 10);

   Int_t nentries = h3333->GetEntries();
   
   for (Int_t i=0; i<nentries;i++) {
      h3333->GetEntry(i);
      for (Int_t ii=0 ; ii<Npart ; ii++) {
   
         if ( TMath::Abs(Kfpar[ii]) == 13 ) {
   
            TVector3  p_muon(Pxpar[ii], Pypar[ii], Pzpar[ii]);

            for ( Int_t iii=0 ; iii<Njeta ; iii++) {

               Double_t rap_muon;

               rap_muon=p_muon.Eta();
               hmj -> Fill(rap_muon);

            }
         }
      }
   }

I've just had a thought on this. Looking in TVector3.h, the constructor
looks like:

TVector3(Double_t x = 0.0, Double_t y = 0.0, Double_t z = 0.0);

The variables Pxpar[ii], etc, are of type Float_t. Is this the problem? I
can't find anywhere that tells me either that ROOT does an implicit
conversion, or how to do a conversion explicitly between these data types,
so I can't check it myself. 

Thanks,
	-Kalen

On Tue, 22 Jan 2002, Rene Brun wrote:

> Hi Kalen,
> 
> I tried converting an old ATLFAST ntuple file into a ROOT file via h2root.
> I generated the analysis code with TTree::MakeCode. 3.02/07 is slightly faster
> than 3.01/06.
> When you moved to 3.02/07, are you sure that you also changed your PATH
> and LD_LIBRARY_PATH variables to point to the new version?
> 
> When you execute TTree::MakeCode, you should have received the following
> warning message:
> 
>  h3333.MakeCode("h3333.C")
> Warning in <TTree::MakeCode>: MakeCode is obsolete. Use MakeClass or
> MakeSelector instead
> 
> Did you modify the generated code? Did you activate/deactivate some branches?
> 
> Rene Brun
> 
> Kalen Martens wrote:
> > 
> > Dear ROOTers,
> > 
> > I was using ROOT version 3.01/06 for some time. Using h2root, I converted
> > a 50K event ntuple made with ATLFAST into a .root file. I used the
> > TTree::MakeCode() method on the root file and created my script which
> > took about 30 seconds to run with version 3.01/06.
> > 
> > I downloaded and installed the binary version 3.02/07. That exact same
> > script now took 10 minutes to run! Another side effect (related, perhaps)
> > is that a segmentation fault occurs when I run this script for the first
> > time after starting ROOT. The segmentation fault is non-fatal and the
> > interpreter recovers.
> > 
> > I can't figure out where the speed is lost and why the segmentation fault
> > occurs. Maybe it's a backwards non-compatability? Any idea would be
> > appreciated.
> > 
> > I'm back using 3.01/06 for now.
> > 
> > Thanks,
> >         -Kalen
> > 
> > -----------------------------------------------------------------
> > - Kalen Martens                              Ph:(416)-978-6632  -
> > - Dept. of Physics                                              -
> > - University of Toronto, Toronto, Canada                        -
> > -----------------------------------------------------------------
> 



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