Re: Few questions about PROOF

From: Antonio Bulgheroni <antonio.bulgheroni_at_gmail.com>
Date: Fri, 5 Jan 2007 10:03:26 +0100


Dear Fons and Constantin,

       thanks for your fast reply. In this days I'll try to see how sucimaPix has to be modified to be compatible with the PROOF approach. I had a very brief look at TAM, I think that it's doing exactly what I need; but I fear that introducing it in my framework is more similar to a revolution than to a small modification. Anyhow, I'll give it a try!

One more (silly) question:

Thanks a lot!

Regards,

Antonio

-- 
Antonio Bulgheroni, PhD
INFN - Roma III

On 1/4/07, Constantin Loizides <loizides_at_mit.edu> wrote:

>
> Dear Antonio,
>
> some of your questions relating the output and the list handling
> of proof maybe solved by our TAM (tree analysis package) that
> allows you to develop analysis classes for hierachical
> analyses transparent to proof, eg with/without running
> on proof.
>
> You may want to peek at
> http://higweb.lns.mit.edu/tam/
>
> where you find some documentation plus the code.
>
> Let me know if you plan to use it since
> there might be some pitfalls on the way
> that I could help you with.
>
> Regards,
> Constantin
>
>
> Antonio Bulgheroni wrote:
> > Dear ROOTers,
> >
> > first of all let me wish you all the best for the new year!
> >
> > I'm writing you because I'm trying to better understand the way
> > PROOF works since it seems to fit all my requirements for parallel event
> > analysis. I'm collaborating in a pretty big standalone ROOT-based code
> > with some tens of classes for data analysis of pixel detectors (
> > sucimaPix <http://groups-beta.google.com/group/sucimaPix-dev>). Even if
> > it is in principle possible to load sucimaPix shared libraries into a
> > ROOT interactive session and run the analysis job from the command line,
> > we prefer to build some executables running in standalone mode. I'm
> > using ROOT 5-15/01 on a linuxx8664 box with gcc 4.1.1. Here come my
> > questions:
> >
> > * If I got it right, the best way to exploit PROOF is via a
> > TSelector derived class. That's not a problem since my input data
> > are already saved into a TTree, so I just need to produce the
> > skeleton of a TSelector and fill in the empty methods. Then I can
> > successfully run the TSelector from my standalone program adding
> > a line like:
> >
> > MyTree->Process(MySelector);
> >
> > In the case I want to run it on PROOF, I added at the beginning a line
> > like this:
> >
> > TProof::Open("localhost");
> >
> > (the PROOF server is properly set-up and the two processors of my PC are
> > found)
> >
> > But, first of all, I wasn't able to compile/link my code using the
> > standard `root-config --cflags --libs` command because it was
> > complaining that the library containing Proof was missing.
> > Using the trial and error approach, I managed to have it working adding
> > the following libs
> >
> > -lProof -lThread -lTreePlayer
> >
> > Is that correct? is there a smarter way? Is it possible to use PROOF
> > from outside an interactive ROOT session? Is it enough to add the
> > TProof::Open() statement to have the Process() worked out by the
> > cluster? or should I do something more?
> >
> > * I tried to understand how PROOF works and I guessed that each
> > slave has to have its own copy of the input file. Is it right? In
> > the case of a single host cluster with a multiple-processor is it
> > true as well? Is a step-by-step tutorial for PROOF available
> > somewhere?
> >
> > * In my analysis procedure I have several histograms to be booked
> > and filled. I believe that all these objects must be added to the
> > fOutput list in order to have the different slave contributions
> > merged together at the end. Is it correct? Is it true for all
> > objects having a Merge() method? Should the booking be done in the
> > Begin() or in the SlaveBeginning() method?
> >
> > * In my original analysis procedure I had a TList containing a set
> > of reference histograms related to the full pixel detector and a
> > certain variable number of other TList containing the same
> > histograms as the main one but concerning only a region of the
> > detector. To solve this problem I created a TList containing TList
> > of histograms. In this way, looping on all the entries of the
> > outer list, I can fill the histos of the sub-region. Is there a
> > way to make it compatible with the PROOF mechanism of the fOutput
> > list? If I add a TList MyList to fOutput, the content of MyList
> > will be merged at the end?
> >
> > Thank you very much for your precious help!
> >
> > Best regards,
> >
> >
> > --
> > Antonio Bulgheroni, PhD
> > INFN - Sez. Roma III
>
> --
> Tel: +1-617-8301823 (SkypeIn)
> Skype: loizides
> AOL: ConLoi / ICQ: 114824520
>
Received on Fri Jan 05 2007 - 10:04:00 CET

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