Hi Christian,
Interesting investigation !
I have access to a dual processor machine running RH6.1 and egcs2.91.66
Could you send me a small data file and a short macro still reproducing the
crash?
Rene Brun
Christian Holm Christensen wrote:
>
> Hi ROOT'ers et al,
>
> I'm experiencing a very strange error when I compile a class for
> handling a ROOT file with a TTree in it. Basically the class opens a
> TFile and creates a TTree in it.
>
> On a single processor i386, running GNU/Linux (Redhat 6.2), using 2nd
> level optimisation (-O2), ROOT 3.01/06, everything works fine.
>
> On a dual processor i386, runnning GNU/Linux (Redhat 6.1), using the
> same optimisation and ROOT version, the class crashed with SIGSEGV
> after lines like:
>
> fTree = new TTree("T","BRAT Event Tree");
> fTree->SetAutoSave(5000000); // autosave when 5 Mbyte written
>
> Running the program in the debugger says that the SIGSEGV comes from
>
> 0x413f509f in TTreePlayer::Scan ()
>
> and a trace gives
>
> #0 0x413f509f in TTreePlayer::Scan ()
> from /afs/rhic/opt/brahms/new/lib/libTreePlayer.so
> #1 0x40a20a91 in TTree::Scan ()
> from /afs/rhic/opt/brahms/new/lib/libTree.so.3.01
> #2 0x40dc86bf in BrEventIO::InitializeRootTreeFile ()
>
> (BrEventIO is the class in question). Now, looking through the code,
> I see absolutly no where where the message TTree::Scan is send. The
> code continues like
>
> BrEvent *dummy = new BrEvent("ev",0,0);
> fBranch = fTree->Branch("event","BrEvent", &dummy,fBufsize,fSplit);
> delete dummy;
>
> Then I tried to compile the class in question on the SMP GNU/Linux
> machine with only first level optimisation (-O1) and no optimisation,
> and everything works smoothly.
>
> I know the compiler on Redhat 6.1 is really old
>
> gcc version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)
>
> and probably a newer compiler will do the trick. However, that is not
> an option in our case. Also, when I compiled ROOT I used the
> linuxegcs configuration which also only has 1st level optimisation.
>
> I searched ROOT talk for anything pertaining to the GCC optimisation,
> but only found
>
> http://root.cern.ch/cgi-bin/print_hit_bold.pl/root/roottalk/roottalk00/2581.html?Optimization#first_hit
>
> which seems to be the same problem, but Rene's answer that didn't
> really help much (quite understandable, since this is probably a very
> compiler/os/machine specific thing).
>
> So the question is: Has anyone else seen this? Does anyone know what
> could be wrong?
>
> And also: Heads up to those using Redhat 6.1 on an SMP machine!
>
> Yours,
>
> Christian -----------------------------------------------------------
> Holm Christensen Phone: (+45) 35 35 96 91
> Sankt Hansgade 23, 1. th. Office: (+45) 353 25 305
> DK-2200 Copenhagen N Web: www.nbi.dk/~cholm
> Denmark Email: cholm@nbi.dk
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