Dear Axel,
great many thanks for taking the time to look into the matter! I'll be good and keep in mind to initialize all pointers. Now I know the source of the problem, I understand that the stacktrace is pointing in this direction:
#13 0xb71e9c90 in TClass::Destructor(void*, bool) () #14 0xb626a2d9 in TBufferFile::ReadFastArray() #15 0xb632b687 in int TStreamerInfo::ReadBuffer<char**>()
Please allow me another question: To avoid this problem once and for all, I've tried to hack together an automatic initialisation like that:
void
GenericSelector::InitializeDataMembers() {
TClass *cl = IsA();
TList *l = cl->GetListOfDataMembers();
TIter next( l );
TObject *obj;
while ( (obj = next()) ) {
const TDataMember *member = dynamic_cast<TDataMember*>( obj );
if ( member && member->IsaPointer() ) {
TString type( member->GetFullTypeName() );
if ( type.BeginsWith( "TH1" ) ) {
char *ptr = (char*)this + member->GetOffset();
*ptr = NULL;
}
}
But it fails miserably. (Interestingly, the point of failure seems to be at the GetOffset() call, not at the access to *ptr.) Do I really need to create an accessor for every member or is there an easier way?
Thank you and kind regards,
Thiemo
On 12/09/2011 02:58 PM, Axel Naumann wrote:
> Some members were uninitialized. As you know, you can read data from a
> TFile into an existing object (think "Event" in a TTree). And you can
> re-read, into the same object. Reading the old object, ROOT might have
> initialized the member TH2D* fBeamPdY_nocut by creating a histogram, and
> having fBeamPdY_nocut point to it. Which means when reading the next
> object it first needs to delete the histogram fBeamPdY_nocut points to.
>
> You happen to not initialize fBeamPdY_nocut in the constructor, which
> means ROOT has no way of knowing that this was in fact not allocated.
> Simply add initializers for the missing members.
>
> This is what I used to scan through your list of members:
> $ grep -E '\*f[[:alnum:]_]+;' /build/tmp/Selector.h | sed -E
> 's,^.*\*(f[[:alnum:]_]+);.*$,\1,' |sort> Thiemo_vars.txt
> $ grep -E '^ *f[[:alnum:]_]+ *\(' /build/tmp/Selector.h | sed -E 's,^
> *(f[[:alnum:]_]+) *\(.*$,\1,' |sort> Thiemo_init.txt
> $ diff -u0 Thiemo_vars.txt Thiemo_init.txt |less
>
> "+" will be initializers for variables that are non-pointers (because
> Thiemo_vars.txt only contains pointer vars). "-" will be the ones you
> still need to initialize.
>
> Let us know if that didn't fix it.
>
> Cheers, Axel.
>
>
> Thiemo Nagel wrote on 11/30/2011 06:18 PM:
>> Dear ROOTers,
>>
>> I'd kindly ask for your help with some crashes that I'm observing with
>> some of my code running with ROOT 5.30.03. I guess that the problem is
>> on my side, but I can't figure out what is wrong.
>>
>> Starting point: I'm storing the output of my analysis in a customized
>> "Selector" class which inherits from "MySelector" which inherits from
>> TSelector. To determine some physical quantities, I'd like to divide
>> the output of two analysis runs, which means that I'm trying to read two
>> Selector objects from two different .root files. But this is already
>> causing crashes. (I've tested that both selectors work well, when the
>> files are opened individually. It's just when both are accessed in the
>> same script that the problem occurs.)
>>
>> testpol.C is a minimal script which triggers my problem.
>> prepareSelectors.C must be called beforehand in order to load all
>> classes into CINT. (For some reason, interpreting the class fails.)
>> I've also attached MySelector.h and Selector.h, in case that might be
>> useful for diagnosis.
>>
>> Any help would be greatly appreciated!
>>
>> Cheers,
>> Thiemo
>>
>> P.S.: Below is the output of one of the crashes:
>>
>> [0] mnemosyne:~/analysis/selector> root -n prepareSelectors.C testpol.C
>> root [0]
>> Processing prepareSelectors.C...
>> 0.177548 s
>> 0.215103 s
>> 0.243131 s
>> 0.269481 s
>> 0.295701 s
>> 0.323266 s
>> 0.35179 s
>> 0.379835 s
>> 0.408063 s
>> 0.449982 s
>> Processing testpol.C...
>> TFile** murd.root
>> TFile* murd.root
>> KEY: Selector Selector;1
>> got Selector: 'murd'
>> TFile** mumc.root
>> TFile* mumc.root
>> KEY: Selector Selector;1
>>
>> *** Break *** segmentation violation
>>
>>
>>
>> ===========================================================
>> There was a crash.
>> This is the entire stack trace of all threads:
>> ===========================================================
>> #0 0xb7779424 in __kernel_vsyscall ()
>> #1 0xb65c9003 in __waitpid_nocancel ()
>> at ../sysdeps/unix/syscall-template.S:82
>> #2 0xb656ae63 in do_system (line=<value optimized out>)
>> at ../sysdeps/posix/system.c:149
>> #3 0xb66863bd in system (
>> line=0xb909630 "/usr/local/root/root_v5.30.03/etc/gdb-backtrace.sh
>> 3137 1>&2") at pt-system.c:29
>> #4 0xb72203cd in TUnixSystem::Exec(char const*) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #5 0xb722716b in TUnixSystem::StackTrace() ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #6 0xb72259af in TUnixSystem::DispatchSignals(ESignals) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #7 0xb7225abd in ?? () from
>> /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #8 0xb721cdc2 in ?? () from
>> /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #9 0xb724bffd in textinput::TerminalConfigUnix::HandleSignal(int) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #10 0xb724c3d6 in ?? () from
>> /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #11<signal handler called>
>> #12 0xb5a46c1d in ?? () from
>> /usr/local/root/root_v5.30.03/lib/libHist.so.5.30
>> #13 0xb71e9c90 in TClass::Destructor(void*, bool) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #14 0xb626a2d9 in TBufferFile::ReadFastArray(void**, TClass const*, int,
>> bool, TMemberStreamer*, TClass const*) ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #15 0xb632b687 in int TStreamerInfo::ReadBuffer<char**>(TBuffer&, char**
>> const&, int, int, int, int) () from
>> /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #16 0xb62ae1a9 in TStreamerInfoActions::GenericAction(TBuffer&, void*,
>> TStreamerInfoActions::TConfiguration const*) ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #17 0xb626439c in
>> TBufferFile::ReadSequence(TStreamerInfoActions::TActionSequence const&,
>> void*) () from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #18 0xb626486b in TBufferFile::ReadClassBuffer(TClass const*, void*,
>> TClass const*) () from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #19 0xb44d674e in Selector::Streamer(TBuffer&) ()
>> from /tmp/tnagel/aclic_builddir/Selector_cc.so
>> #20 0xb62a1afb in TKey::ReadObj() ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #21 0xb62751f1 in TDirectoryFile::Get(char const*) ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #22 0xb727159e in ?? () from
>> /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #23 0xb6a7f0f7 in Cint::G__ExceptionWrapper(int (*)(G__value*, char
>> const*, G__param*, int), G__value*, char*, G__param*, int) ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #24 0xb6b2e4cf in G__execute_call ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #25 0xb6b2f36a in G__call_cppfunc ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #26 0xb6b09991 in G__interpret_func ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #27 0xb6af61ec in G__getfunction ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #28 0xb6bf6524 in G__getstructmem(int, G__FastAllocString&, char*, int,
>> char*, int*, G__var_array*, int) ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #29 0xb6beafc5 in G__getvariable ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #30 0xb6acfc18 in G__getitem ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #31 0xb6ad51ac in G__getexpr ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #32 0xb6af5694 in G__getfunction ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #33 0xb6ad028b in G__getitem ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #34 0xb6ad51ac in G__getexpr ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #35 0xb6af6a6f in G__getfunction ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #36 0xb6ad028b in G__getitem ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #37 0xb6ad51ac in G__getexpr ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #38 0xb6abf235 in G__define_var ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #39 0xb6b5bc9c in G__exec_statement ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #40 0xb6b0ac7e in G__interpret_func ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #41 0xb6af6251 in G__getfunction ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #42 0xb6ad028b in G__getitem ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #43 0xb6ad51ac in G__getexpr ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #44 0xb6adfe28 in G__calc_internal ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #45 0xb6b6e629 in G__process_cmd ()
>> from /usr/local/root/root_v5.30.03/lib/libCint.so.5.30
>> #46 0xb71de75b in TCint::ProcessLine(char const*,
>> TInterpreter::EErrorCode*) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #47 0xb71dc111 in TCint::ProcessLineSynch(char const*,
>> TInterpreter::EErrorCode*) () from
>> /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #48 0xb71253bc in TApplication::ExecuteFile(char const*, int*, bool) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #49 0xb71256dc in TApplication::ProcessFile(char const*, int*, bool) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #50 0xb7122ae8 in TApplication::ProcessLine(char const*, bool, int*) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #51 0xb68069ca in TRint::Run(bool) ()
>> from /usr/local/root/root_v5.30.03/lib/libRint.so.5.30
>> #52 0x08048ebf in main ()
>> ===========================================================
>>
>>
>> The lines below might hint at the cause of the crash.
>> If they do not help you then please submit a bug report at
>> http://root.cern.ch/bugs. Please post the ENTIRE stack trace
>> from above as an attachment in addition to anything else
>> that might help us fixing this issue.
>> ===========================================================
>> #12 0xb5a46c1d in ?? () from
>> /usr/local/root/root_v5.30.03/lib/libHist.so.5.30
>> #13 0xb71e9c90 in TClass::Destructor(void*, bool) ()
>> from /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> #14 0xb626a2d9 in TBufferFile::ReadFastArray(void**, TClass const*, int,
>> bool, TMemberStreamer*, TClass const*) ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #15 0xb632b687 in int TStreamerInfo::ReadBuffer<char**>(TBuffer&, char**
>> const&, int, int, int, int) () from
>> /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #16 0xb62ae1a9 in TStreamerInfoActions::GenericAction(TBuffer&, void*,
>> TStreamerInfoActions::TConfiguration const*) ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #17 0xb626439c in
>> TBufferFile::ReadSequence(TStreamerInfoActions::TActionSequence const&,
>> void*) () from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #18 0xb626486b in TBufferFile::ReadClassBuffer(TClass const*, void*,
>> TClass const*) () from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #19 0xb44d674e in Selector::Streamer(TBuffer&) ()
>> from /tmp/tnagel/aclic_builddir/Selector_cc.so
>> #20 0xb62a1afb in TKey::ReadObj() ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #21 0xb62751f1 in TDirectoryFile::Get(char const*) ()
>> from /usr/local/root/root_v5.30.03/lib/libRIO.so.5.30
>> #22 0xb727159e in ?? () from
>> /usr/local/root/root_v5.30.03/lib/libCore.so.5.30
>> ===========================================================
>>
>>
>> Root> Function testpol() busy flag cleared
>>
>>
-- +-----------------------------------+--------------------------+ | Dipl.-Phys. Thiemo Nagel | | | Technische Universitaet Muenchen | Room PH1 3276 | | Physik-Department E18 | | | James-Franck-Strasse | Phone +49 89 289-12379 | | D-85747 Garching | Fax +49 89 289-12570 | +-----------------------------------+--------------------------+Received on Wed Dec 14 2011 - 11:41:22 CET
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