Re: how to allow a file-split only at very specific times ?

Philippe,

On Tue, 8 Feb 2011 09:27:55 -0600, Philippe Canal <pcanal_at_fnal.gov> wrote:
> Hi Sebastien,
>
> For data based selection, you might be able to use
> TFile *output_file = TFile:Open(.....);
> TTree *output_tree = input_tree->CopyTree("pz<0"); // Or some other TTree::Draw style selection
> output_file->Write();
> Or if you need more precise/complicated control:
>
> TFile *output_file = TFile:Open(.....);
> TTree *output_tree = input_tree->CloneTree(0);
> for (Int_t i=0;i<input_tree->GetEntries(); i++) {
> input_tree->GetEntry(i);
> if (event->GetNtrack() > 605) output_tree->Fill();
> event->Clear();
> }
> output->file->Write();
>
> See $ROOTSYS/tutorials/tree/copytree* for other examples.
yes, I am well aware of these examples :)

FTR, this is the program I am talking about:  http://alxr.usatlas.bnl.gov/lxr/source/atlas/Tools/PyUtils/bin/filter-and-merge-d3pd.py?v=head

it can remove branches off a tree, apply an entry selection based on the tree's variables or from an external "good run list" (xml! arf!) file.

the problem is that as I am merging (and filtering) many input files and many trees, I may hit the MaxSizeTree limit (and I should at hit it at some point because even if data management likes big files, data migration doesn't like *too big* files) for my output merged file(s) while not having finished to process the entry N for all the trees I am processing...

Looking deeper into the TTree source code, I finally noticed TTree:ChangeFile

 http://root.cern.ch/root/html/src/TTree.cxx.html#2192

which -- I suppose -- I could manually trigger when the max-file size limit is looming...

any road block on this path ?

-- 
@+
-s






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