Re: [ROOT] ROOT 20 times slower

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Jan 22 2002 - 08:35:55 MET


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: MakeCode is obsolete.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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