Re: [ROOT] tree buffer question

From: Peter Elmer (Peter.Elmer@cern.ch)
Date: Mon Jan 05 2004 - 12:54:37 MET


  Hi Rene,

On Wed, Dec 24, 2003 at 11:44:15AM +0100, Rene Brun wrote:
> Did you write your Tree with 3.10/01 or an old version?

  I wrote the tree with ROOT 3.10/01.

> In 3.10/02, I added a fix when reading very old files.
> Could you try with the released version 3.10/02 or tell me where
> I can take one of you files (small file if possible)?

  I've put an example file here:

  /afs/cern.ch/user/e/elmer/public/root/convert5.02E.root

The tree demonstrating the problem is "esd" and the branch (in this example)
with the problem is "Emc_Bumps__n". This tree has 8000 events, just enough
to get to the point where the relevant buffers is compressed. When I run
with fewer events (7000) and the buffer is not yet compressed, I see
that the contents are basically all zeroes with a very small number of 
"1"'s. A standlone test of filling a branch with 0's and 1's doesn't lead
to the same problem.

  I'll setup and try reading with ROOT 3.10/02 even if this is not an old 
file...

                                 thanks,
                                   Pete

> On Tue, 23 
> Dec 
> 2003, Peter Elmer wrote:
> 
> >   Hi,
> > 
> >   Starting recently (probably from ROOT 3.10-01) we have started to see
> > R__unzip errors in reading back tree branches containing only integers. It
> > is a bit complicated so I've not yet succeeded in reducing it to a simple
> > test case, but I already see something strange in looking at a file:
> > 
> > *............................................................................*
> > *Br   19 :Emc_Bumps__n : Emc_Bumps__n/i                                      *
> > *Entries :     6000 : Total  Size=      36446 bytes  One basket in memory    *
> > *Baskets :        0 : Basket Size=      32000 bytes  Compression=   1.00     *
> > *............................................................................*
> > *Br   21 :Emc_Clusters__n : Emc_Clusters__n/i                                *
> > *Entries :     6000 : Total  Size=      36464 bytes  One basket in memory    *
> > *Baskets :        0 : Basket Size=      32000 bytes  Compression=   1.00     *
> > *............................................................................*
> > *Br   23 :Emc_Cands__n : Emc_Cands__n/i                                      *
> > *Entries :     6000 : Total  Size=      36446 bytes  One basket in memory    *
> > *Baskets :        0 : Basket Size=      32000 bytes  Compression=   1.00     *
> > *............................................................................*
> > 
> > Is it normal that the total size would exceed the basket size yet a basket
> > is not compressed and written separately from the tree?
> > 
> >   I recall that you put in some bug fix recently related to compression of
> > branches containing integers, could you remind me what was that fix?
> > 
> >   [For the record, we are working on Linux (RH7.2) with gcc 2.95.3.]
> > 
> >                                  thanks,
> >                                    Pete



-------------------------------------------------------------------------
Peter Elmer     E-mail: Peter.Elmer@cern.ch      Phone: +41 (22) 767-4644
Address: CERN Division PPE, Bat. 32 2C-14, CH-1211 Geneva 23, Switzerland
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