I have a following C++ code which uses PyObject_CallObject to evaluate
expressions dynamically. This code sets the input parameters for the
function also dynamically. After calling this function 4 times (with
these shown values), PyObject_CallObject causes application to crash
in frame_dealloc.
1) Can some one please help me understand why is this crash happening
in frame_dealloc & how to solve it?
2) Is there anything wrong I am doing about incrementing or
decrementing the reference counts of the object passed to
PyObject_CallObject?
3) Is it because of the big value (2299265.500000) I am trying to
convert from double to float using PyFloat_FromDouble?
//========================= code reduced for readability
===============
switch(ndtyp){
case(INT_T):
{
printf("PyInt_FromLong val %d, var %s
\n",inputVar.nionum,pEvalFunc->pExprVarsArray[nCtr].szVarName);
val = PyInt_FromLong(inputVar.nionum);
break;
}
case(LONG_T):
{
printf("PyLong_FromLong val %ld, var %s
\n",inputVar.lionum,pEvalFunc->pExprVarsArray[nCtr].szVarName);
val = PyLong_FromLong(inputVar.lionum);
break;
}
case(FLOAT_T):
{
printf("PyFloat_FromDouble val %f, var %s
\n",inputVar.fionum,pEvalFunc->pExprVarsArray[nCtr].szVarName);
val = PyFloat_FromDouble(inputVar.fionum);
break;
}
case(DOUBLE_T):
{
printf("PyFloat_FromDouble val %f, var %s
\n",inputVar.dionum,pEvalFunc->pExprVarsArray[nCtr].szVarName);
val = PyFloat_FromDouble(inputVar.dionum);
break;
}
case(STRING_T):
{
printf("PyString_FromString val %s, var %s
\n",inputVar.ioString,pEvalFunc->pExprVarsArray[nCtr].szVarName);
val = PyString_FromString(inputVar.ioString);
break;
}
default:
printf("Unknown data type [%d] for %s\n",ndtyp,pEvalFunc-
>pExprVarsArray[nCtr].szVarName);
}
if(!val){
ret = -1;
printf("Failed to convert %d %s to PyObject\n",ndtyp,pEvalFunc-
>pExprVarsArray[nCtr].szVarName); fflush(stdout);
Py_XDECREF(pTuple);
break;
}
PyTuple_SetItem(pTuple, nCtr, val);
Py_XDECREF(val);
}
// all variables are set, call Python function
Py_XINCREF(pTuple);
PyObject *pResult = PyObject_CallObject(pEvalFunc-
>pPyEvalFunction,pTuple);
Py_XDECREF(pTuple);
if(PyErr_Occurred()){
PyErr_Print();
} else {
char* plevel = NULL;
if(NULL != (plevel = PyString_AsString(pResult))){
ret = 0;
sprintf(szEvalResult,"%s",plevel);
}
}
Py_XDECREF(pResult);
================================================
Following crash (back trace) appears when I run this in GDB. The
expression that was getting evaluated at this time is:
def DangerousQuantity(size,maxvol,adv):
if((size<1000 and (maxvol<10000) and (size<0.001*adv))):
return "Dangerous"
else:
return "FAIL"
//--------------- Crash dump information & values of variables passed
to this expression
Categorizing the order
pyParserEvaluator evaluating category function DangerousTactic
PyString_FromString val R, var aestactic
PyLong_FromLong val 1139, var endtime
PyLong_FromLong val 599, var starttime
PyLong_FromLong val 23, var Aggr
PyObject_CallObject done, do Py_XDECREF-pTuple
Final result FAIL
doing Py_XDECREF(pResult
pyParserEvaluator evaluating category function MediumTactic
PyString_FromString val R, var aestactic
PyLong_FromLong val 1139, var endtime
PyLong_FromLong val 599, var starttime
PyLong_FromLong val 23, var Aggr
PyObject_CallObject done, do Py_XDECREF-pTuple
Final result FAIL
doing Py_XDECREF(pResult
pyParserEvaluator evaluating category function SafeTactic
PyString_FromString val R, var aestactic
PyLong_FromLong val 1139, var endtime
PyLong_FromLong val 599, var starttime
PyLong_FromLong val 23, var Aggr
PyObject_CallObject done, do Py_XDECREF-pTuple
Final result FAIL
doing Py_XDECREF(pResult
pyParserEvaluator evaluating category function DangerousQuantity
PyLong_FromLong val 1, var size
PyLong_FromLong val 0, var maxvol
PyFloat_FromDouble val 2299265.500000, var adv
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 82336688 (LWP 27652)]
0xc0000000 in ?? ()
(gdb) where
#0 0xc0000000 in ?? ()
#1 0x0285e59e in frame_dealloc (f=0xf5a2f68c) at Objects/
frameobject.c:106
#2 0x0281a4b1 in PyEval_EvalCodeEx (co=0xf5a69990, globals=0x2884120,
locals=0x0, args=0x288bca0, argcount=3, kws=0x0, kwcount=0,
defs=0x0, defcount=0, closure=0x0) at Python/ceval.c:2609
#3 0x0285f551 in function_call (func=0xf5a694c4, arg=0xf5a47c3c,
kw=0x0) at Objects/funcobject.c:476
#4 0x027e1e04 in PyObject_Call (func=0xf5a2003c, arg=0xf5a47c3c,
kw=0x0) at Objects/abstract.c:1688
#5 0x0281b3eb in PyEval_CallObjectWithKeywords (func=0xf5a694c4,
arg=0xf5a47c3c, kw=0x0) at Python/ceval.c:3058
#6 0x027e1de3 in PyObject_CallObject (o=0xf5a694c4, a=0xf5a47c3c) at
Objects/abstract.c:1679
#7 0x027dd6fd in pyParserEvaluator::EvaluateCategory
(this=0xf5a08df0, nCatLevelId=1, pOrdData=0x4e84f40,
szEvalResult=0x4e84b70 "Dangerous") at pyEvaluator.cpp:342
#8 0x0070da71 in ParseEvalDriver::categorizeOrder (this=0xf5a0cf20,
pcatRuleCache=0xfeff4e20, pOrdData=0x4e84f40,
szLevelResult=0x9876180) at IEvaluatorInterface.cpp:102
#9 0x0807e812 in HandleCheck (szTopic=0x96d0439 "CE/REQ_3_EX/NEW",
szReplyTopic=0x96d0639 "CE/RES_3_EX/njl36a-7003_401",
pBuff=0x9875688 "4056029121", nBuffLen=195, pUsr=0xfeff4e18) at
cerule.cpp:4859
#10 0x0032130d in CMiTssSub::OnRecvMsg (this=0xf5aaf0b0,
pszTopic=0x96d0439 "CE/REQ_3_EX/NEW",
pszReplyTopic=0x96d0639 "CE/RES_3_EX/njl36a-7003_401",
pmsg=0x98754e8) at src/mitss.cpp:1810
#11 0x0031dc01 in CMiTss::OnRecvMsg (pszTopic=0x96d0438 "/CE/REQ_3_EX/
NEW",
pszReplyTopic=0x96d0638 "/CE/RES_3_EX/njl36a-7003_401",
pszMsg=0x98755e8 "èT\207\tèT\207\t", nMsgLen=4, pUsr=0xf5aaf0b0)
at src/mitss.cpp:466
#12 0x0032296c in CMiHelper::_worker (arg=0x96cfc44) at mihelper.cpp:
390
#13 0x00339701 in _vmt_proc (thread_arg=0x96d0250) at vmt.c:347
#14 0x002afdec in start_thread () from /lib/tls/libpthread.so.0
#15 0x00603a2a in clone () from /lib/tls/libc.so.6
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