Re: [ROOT] write a big Tree in a TFile

From: Rene Brun (Rene.Brun@cern.ch)
Date: Mon Sep 29 2003 - 10:12:32 MEST


I am afraid that we will not make any progress without looking at a simplified
version of your code reproducing this problem.

Rene Brun

Matthieu Lechowski wrote:
> 
> Hello,
> Thanks, but unfortunately it doesn't work.
> The first solution doesn't change anything, and with the second ROOT
> tells me my file is not writable (Error in <TTree::Write>: File ... is
> not writable).
> Have you others ideas ?
> Thank you.
> 
> Matthieu.
> 
> On Fri, 26 Sep 2003, Rene Brun wrote:
> 
> > Matthieu,
> >
> > This seems to be a problem with the destructor of your TTree when
> > you close the file.
> > You can try two solutions:
> >  1- after TREE.Write(); add the statement
> >     TREE.SetFile(0);
> >
> >  2- Do not create your Tree in the stack, but in the heap with
> >    TFile *myfile=new TFile(name_ntuple, "RECREATE");
> >    TTree *TREE = new TTRee(...
> >    //..fill tree
> >    TREE->Write();
> >    delete myfile; //do not delete TREE
> >
> > Rene Brun
> >
> > Matthieu Lechowski wrote:
> > >
> > > Hello,
> > >
> > > ROOT leaves without saying anything when I try to write a TTree in a
> > > TFile, and the file has only few bytes (and can not be opened of
> > > course).
> > >
> > > I have a global tree: TTree TREE("T","TREE");
> > > In a function, I fill it, then:
> > >  TFile *myfile=new TFile(name_ntuple, "RECREATE");
> > >  TREE.Write();
> > >  myfile->Close();
> > >
> > > This is the way I always used, and it always worked, but this time I
> > > have a big Tree and this doesn't work, I don't know why.
> > > Its size is less than the limit 2Gb, I think it should be around 80Mb
> > > with 100.000 entries (I have already a similar file of 8Mb with 10.000
> > > entries that I succeeded to write).
> > >
> > > Have you an idea of what goes wrong ?
> > > Thank you.
> > >
> > >         Matthieu Lechowski
> > >         LAL Orsay
> > >
> > > lxplus
> > > ROOTSYS=/afs/cern.ch/sw/root/v3.05.05/rh73_gcc2952/root
> >



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