TMapFile

From: Piergiorgio Cerello (cerello@to.infn.it)
Date: Fri Aug 28 1998 - 10:35:00 MEST


Dear rooters,

I get a segmentation fault when trying to open a memory mapped file.

Here is the producer's code:

...

   TH1F *lmdmult;

...

   TMapFile *mmap = TMapFile::Create("lmd.map","RECREATE", 2000000,"Lmd
memory mapped file with histograms");
   mmap->Print();

...

    lmdmult = new TH1F("lmdmult","lmd multiplicity",200,-0.5,199.5);

...

    (loop)  {

...

        lmdmult->Fill((Float_t) nhlmd);

...

	 mmap->Update();
         mmap->ls();
         }


The output is:


Memory mapped file:   lmd.map
Title:                Lmd memory mapped file with histograms
Option:               CREATE
Mapped Memory region: 0x407a7000 - 0x4098f480 (1.91 MB)
Current breakval:     0x407af000

...

lmdmult              TH1F                 1320    (from mmap->ls();)



When I try to access the lmd.map file from a ROOT session, I give:

 TMapFile *mfile = TMapFile::Create("lmd.map");

and I get back:

Segmentation fault
bash$

Something different happens if I give a small size to the .map file.
With 20000 istead of 2000000, I can access the file from the consumer,
but I get a segmentation fault when I try to update it from the producer.

Any suggestion?

Thanks,

   Piergiorgio



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