cant figure out segmentation fault using boost threads - c++

Question

I'm developing a stomp client in c++ using boost library for sockets and threads.
The program consists of two major classes SocketListener which gets frame from the socket and UserInterface which receives commands from the user and sends frames to the server.
I can't figure out a segmentation fault i get when i shutdown the SocketListener. (when i call the shutdown method)
Using valgrind i get this error:
==8450== Thread 2:
==8450== Invalid read of size 8
==8450== at 0x588AF8B: std::string::assign(std::string const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.16)
==8450== by 0x417846: SocketListener::shutdown(std::string) (SocketListener.cpp:114)
==8450== by 0x41D2A7: userInterface::shutdown() (UserInterface.cpp:123)
==8450== by 0x41C7ED: userInterface::run() (UserInterface.cpp:37)
==8450== by 0x415F0B: boost::_mfi::mf0<void, userInterface>::operator()(userInterface*) const (mem_fn_template.hpp:49)
==8450== by 0x415DF1: void boost::_bi::list1<boost::_bi::value<userInterface*> >::operator()<boost::_mfi::mf0<void, userInterface>, boost::_bi::list0>(boost::_bi::type<void>, boost::_mfi::mf0<void, userInterface>&, boost::_bi::list0&, int) (bind.hpp:253)
==8450== by 0x415B4E: boost::_bi::bind_t<void, boost::_mfi::mf0<void, userInterface>, boost::_bi::list1<boost::_bi::value<userInterface*> > >::operator()() (bind_template.hpp:20)
==8450== by 0x4157E7: boost::detail::thread_data<boost::_bi::bind_t<void, boost::_mfi::mf0<void, userInterface>, boost::_bi::list1<boost::_bi::value<userInterface*> > > >::run() (thread.hpp:74)
==8450== by 0x5046C2C: thread_proxy (in /usr/local/boost/1.51.0/lib/libboost_thread.so.1.51.0)
==8450== by 0x5260E99: start_thread (pthread_create.c:308)
==8450== by 0x5DF53FC: clone (clone.S:112)
==8450== Address 0x50 is not stack'd, malloc'd or (recently) free'd
==8450==
==8450==
==8450== Process terminating with default action of signal 11 (SIGSEGV)
==8450== Access not within mapped region at address 0x50
==8450== at 0x588AF8B: std::string::assign(std::string const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.16)
==8450== by 0x417846: SocketListener::shutdown(std::string) (SocketListener.cpp:114)
==8450== by 0x41D2A7: userInterface::shutdown() (UserInterface.cpp:123)
==8450== by 0x41C7ED: userInterface::run() (UserInterface.cpp:37)
==8450== by 0x415F0B: boost::_mfi::mf0<void, userInterface>::operator()(userInterface*) const (mem_fn_template.hpp:49)
==8450== by 0x415DF1: void boost::_bi::list1<boost::_bi::value<userInterface*> >::operator()<boost::_mfi::mf0<void, userInterface>, boost::_bi::list0>(boost::_bi::type<void>, boost::_mfi::mf0<void, userInterface>&, boost::_bi::list0&, int) (bind.hpp:253)
==8450== by 0x415B4E: boost::_bi::bind_t<void, boost::_mfi::mf0<void, userInterface>, boost::_bi::list1<boost::_bi::value<userInterface*> > >::operator()() (bind_template.hpp:20)
==8450== by 0x4157E7: boost::detail::thread_data<boost::_bi::bind_t<void, boost::_mfi::mf0<void, userInterface>, boost::_bi::list1<boost::_bi::value<userInterface*> > > >::run() (thread.hpp:74)
==8450== by 0x5046C2C: thread_proxy (in /usr/local/boost/1.51.0/lib/libboost_thread.so.1.51.0)
==8450== by 0x5260E99: start_thread (pthread_create.c:308)
==8450== by 0x5DF53FC: clone (clone.S:112)
==8450== If you believe this happened as a result of a stack
==8450== overflow in your program's main thread (unlikely but
==8450== possible), you can try to increase the size of the
==8450== main thread stack using the --main-stacksize= flag.
==8450== The main thread stack size used in this run was 8388608.
here is the code:
main.cpp:
main() {
StompClient* client = new StompClient();
userInterface* ui = new userInterface(client); // this doesnt invoke the segfault but SocketListener::shutdown() is called from this object
SocketListener* socketListener = new SocketListener(client,ui);
boost::thread* uiThread = new boost::thread(&userInterface::run, ui);
boost::thread* socketThread= new boost::thread(&SocketListener::run, socketListener);
socketThread->join();
uiThread->join();
}
SocketListener.h:
class SocketListener {
public:
SocketListener(StompClient* client, userInterface* ui);
virtual ~SocketListener();
void run();
void exportHtml();
void processMessage(StompFrame* frame);
void shutdown(string* fileName);
private:
StompClient* _client;
bool _shutdown;
userInterface* _UI;
string _userName;
};
SocketLisener.cpp:
void SocketListener::run() {
StompParser parser;
StompFrame* frame = 0;
while (!_shutdown) {
if (frame != 0) {
delete frame;
}
frame = _client->getFrame();
if (frame == 0) {
continue;
}
//switch on all the messages cases. the problem happens regardless of message type, even when not receiving anything.
}
void SocketListener::exportHtml() {
//writing to file using poco logger
}
void SocketListener::shutdown(string* fileName) {
cout << "shutting down socket listener" <<endl;
_userName = *fileName; // this is line 114 which valgrind points to
_shutdown = true;
cout << "shutting down socket listener2" <<endl; // this line never gets printed
}