[boost-python]Python callback called from C++ thread is crashing - boost-python

Question

I have a C++ class to which a python class object is passed as an argument.
My c++ code is calling a python function using the stored python object of that class. The python function returns a python dictionary to my C++ function. C++ function further extract values from that python dictionary for further use.
A code snippet is like the below:
C++ Code snippet:
enter code here
class Wrapper
{
private:
boost::python::object pyObj;
public:
Wrapper(boost::python::object pyObj):pyObj(pyObj)
{
}
~Wrapper()
{
}
// Executed in thread and calls python callback
void getPythonDict()
{
PyGILState_STATE state = PyGILState_Ensure();
boost::python::object pathInfoDict = this->pyObj.attr("getPathDict")(jobid, (uint_t)iostatus);
bool_t status = boost::python::extract<bool_t>(pathInfoDict["status"]);
PyGILState_Release(state);
}
};
class Core
{
public:
Core(){}
~Core(){}
void callCPlusPlusFunction(boost::python::object &pyObj)
{
Wrapper *ptr = new Wrapper(pyObj);
// launch the getPythonDict function in thread and return back to python function
// boost::thread is used for launching thread
}
};
Python Code snippet:
class PyCallback:
def __init__(self):
pass
def getPathDict(self, jobid, iostatus):
pyDict = {}
pyDict ['status'] = True
return pyDict
from libCore import Core <------C++ library exposed as python module
class PyManager:
def __init__(self):
self.pyCallback = PyCallback()
self.cObj = Core() <---------------Object of C++ "class Core"
def gateWayToCPlusPlusCall(self):
self.cObj.callCPlusPlusFunction(self.pyCallback)
I am using boost::python::object in C++ to store the python object.
After my c++ method calls the python function, the python callback is crashing sometimes.
Below is the analysis of the core file.
<enter code here>
#0 0x0000003e52a80036 in PyObject_Malloc () from /usr/lib64/libpython2.6.so.1.0
#1 0x0000003e52a87a4a in PyString_FromStringAndSize () from /usr/lib64/libpython2.6.so.1.0
#2 0x0000003e52aee0e8 in ?? () from /usr/lib64/libpython2.6.so.1.0
#3 0x0000003e52aee613 in ?? () from /usr/lib64/libpython2.6.so.1.0
#4 0x0000003e52aee722 in ?? () from /usr/lib64/libpython2.6.so.1.0
#5 0x0000003e52aeeaff in Py_BuildValue () from /usr/lib64/libpython2.6.so.1.0
#6 0x0000003e52ae6a51 in ?? () from /usr/lib64/libpython2.6.so.1.0
#7 0x0000003e52ad5916 in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#8 0x0000003e52ad6b8f in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#9 0x0000003e52ad6b8f in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#10 0x0000003e52ad7657 in PyEval_EvalCodeEx () from /usr/lib64/libpython2.6.so.1.0
#11 0x0000003e52ad5aa4 in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#12 0x0000003e52ad7657 in PyEval_EvalCodeEx () from /usr/lib64/libpython2.6.so.1.0
#13 0x0000003e52ad5aa4 in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#14 0x0000003e52ad6b8f in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#15 0x0000003e52ad6b8f in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#16 0x0000003e52ad6b8f in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#17 0x0000003e52ad7657 in PyEval_EvalCodeEx () from /usr/lib64/libpython2.6.so.1.0
#18 0x0000003e52ad5aa4 in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#19 0x0000003e52ad7657 in PyEval_EvalCodeEx () from /usr/lib64/libpython2.6.so.1.0
#20 0x0000003e52ad5aa4 in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#21 0x0000003e52ad6b8f in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#22 0x0000003e52ad6b8f in PyEval_EvalFrameEx () from /usr/lib64/libpython2.6.so.1.0
#23 0x0000003e52ad7657 in PyEval_EvalCodeEx () from /usr/lib64/libpython2.6.so.1.0
#24 0x0000003e52a6acb0 in ?? () from /usr/lib64/libpython2.6.so.1.0
#25 0x0000003e52a43c63 in PyObject_Call () from /usr/lib64/libpython2.6.so.1.0
#26 0x0000003e52a566af in ?? () from /usr/lib64/libpython2.6.so.1.0
#27 0x0000003e52a43c63 in PyObject_Call () from /usr/lib64/libpython2.6.so.1.0
#28 0x0000003e52acfc93 in PyEval_CallObjectWithKeywords () from /usr/lib64/libpython2.6.so.1.0
#29 0x0000003e52aee98a in PyEval_CallFunction () from /usr/lib64/libpython2.6.so.1.0
#30 0x00007f2a84665123 in boost::python::call<boost::python::api::object, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, unsigned int> (callable=0x24c55a0, a0=<value optimized out>, a1=<value optimized out>)
at /usr/include/boost141/boost/python/call.hpp:66
#31 0x00007f2a84663885 in operator()<ddsCore::jobid_t, ddsCore::uint_t> (this=0x7f2a5049c2a0, pathInfo=..., jobid=...,
iostatus=ddsCore::IO_STATE_SUCCESS) at /usr/include/boost141/boost/python/object_call.hpp:19
#32 ddsCore::multiPath::PathManagerWrapper::getPathInformation (this=0x7f2a5049c2a0, pathInfo=..., jobid=...,
iostatus=ddsCore::IO_STATE_SUCCESS) at src/ddsCore/src/pathManagerWrapper.cpp:21
#33 0x00007f2a8465e6f9 in ddsCore::multiPath::PathFailoverHandler::pathFailoverSubroutine (this=0x7f2a506474b0, pathInfo=..., jobid=...,
iostatus=ddsCore::IO_STATE_SUCCESS) at src/ddsCore/src/pathFailoverInterface.cpp:50
#34 0x00007f2a8465fca7 in ddsCore::multiPath::PathFailoverManager::executePathFailoverHandler (this=0x7f2a5048f260)
at src/ddsCore/src/pathFailoverManager.cpp:86
#35 0x00007f2a84624d93 in ddsCore::ioLayerUnit::AsynchronousReaderInterface::requestResubmitter (this=0x7f2a5043e8a0)
at src/ddsCore/src/ioWorkers.cpp:524
#36 0x00007f2a8466259a in operator() (this=<value optimized out>) at /usr/include/boost141/boost/function/function_template.hpp:1013
#37 boost::detail::thread_data<boost::function<void()> >::run(void) (this=<value optimized out>)
at /usr/include/boost141/boost/thread/detail/thread.hpp:56
#38 0x00007f2a83e55d10 in thread_proxy () from /usr/lib64/libboost_thread- mt.so.1.41.0
#39 0x0000003e51a079d1 in start_thread () from /lib64/libpthread.so.0
#40 0x0000003e512e88fd in clone () from /lib64/libc.so.6
(gdb) frame 0
#0 PyObject_Malloc (nbytes=42) at Objects/obmalloc.c:780
780 if ((pool->freeblock = *(block **)bp) != NULL) {
(gdb) l
775 * Pick up the head block of its free list.
776 */
777 ++pool->ref.count;
778 bp = pool->freeblock;
779 assert(bp != NULL);
780 if ((pool->freeblock = *(block **)bp) != NULL) { <------- crash happened at this point
781 UNLOCK();
782 return (void *)bp;
783 }
784 /*
(gdb) print pool
$3 = (poolp) 0x7f2a58121000
(gdb) print pool->freeblock
$4 = (block *) 0x0
$4 = (block *) 0x0
(gdb) print pool->ref
$5 = {_padding = 0x54 <Address 0x54 out of bounds>, count = 84}
(gdb) print pool->ref.count
$6 = 84
(gdb) print pool->freeblock
$7 = (block *) 0x0 <----------------- Why this pointer is NULL, this is suspicious ????
(gdb) print *pool
$8 = {ref = {_padding = 0x54 <Address 0x54 out of bounds>, count = 84}, freeblock = 0x0, nextpool = 0x7f2a54031000, prevpool =
0x7f2a54031000, arenaindex = 18, szidx = 5, nextoffset = 4080, maxnextoffset = 4048}
Since the python callback is called from a non-python thread so i have ensured PyGILState_STATE as well.
Can any one please help me in this issue !!!!