Error while multithreading in C++ - c++

Question

I am writing to write a program that will make use of multithreading. I tried to read about multithreading and was able to get a sample program working. However I have run into a glitch and I am not sure what is going wrong. I am posting the sample program and will highlight where I am experiencing trouble.
#include <Windows.h>
#include <process.h>
#include <iostream>
#include <cassert>
#include <ctime>
#import "calc.dll" \
auto_rename no_namespace no_smart_pointers \
raw_native_types named_guids
using namespace std;
HANDLE th_mutex;
struct Arguments
{
string case_id;
string file;
};
//____________________________________
unsigned int __stdcall TestThread(void *args)
{
int i = 0,
j = 0;
cout << "Inside thread" << endl;
for (i = 0; i <= 10000; i++)
{
for (j = 0; j <= 100000; j++)
{
}
if (i == 10000)
cout << "The value of i inside the thread = " << i << endl;
}
return EXIT_SUCCESS;
}
//____________________________________
unsigned int __stdcall Thread(void *args)
{
CoInitialize(0);
{
Arguments *input;
input = (Arguments *) args;
time_t current_time;
time(&current_time);
cout << ctime(&current_time) << endl;
IHeatExchangerNetwork *hxNetwork = 0;
IDispatchPtr theUnit = 0;
IHeatTransferUnit *unit = 0;
VARIANT vAppend;
_bstr_t filename,
output;
filename = input->file.c_str();
filename += input->case_id.c_str();
filename += ".dat";
output = input->file.c_str();
output += input->case_id.c_str();
output += ".dbo";
cout << filename << endl;
cout << output << endl;
HRESULT hr = CoCreateInstance(CLSID_HeatExchangerNetwork,
0,
CLSCTX_ALL,
DIID_IHeatExchangerNetwork,
reinterpret_cast<void**>(&hxNetwork));
theUnit = hxNetwork->LoadHeatTransferUnit(filename, HxUnitTypeKey::HxUnitTypeCrossflow);
hr = theUnit->QueryInterface(DIID_IHeatTransferUnit, reinterpret_cast<void**>(&unit));
hxNetwork->Run(0, 0);
vAppend.boolVal = false;
unit->WriteDBOFile(output, OutputData, vAppend);
time(&current_time);
cout << ctime(&current_time) << endl;
}
CoUninitialize();
return EXIT_SUCCESS;
}
//____________________________________
int main()
{
DWORD retval;
Arguments args[2];
args[0].case_id = "1";
args[0].file = "C:\\Documents and Settings\\User\\My Documents\\Test Cases\\1\\";
args[1].case_id = "2";
args[1].file = "C:\\Documents and Settings\\User\\My Documents\\Test Cases\\2\\";
th_mutex = CreateMutex(NULL, FALSE, NULL);
if (th_mutex == NULL)
{
printf("CreateMutex error: %d\n", GetLastError());
return 1;
}
// ================================
// Basic testing of calling threads
// ================================
HANDLE hnd1;
cout << "Before creating new thread" << endl;
hnd1 = (HANDLE) _beginthreadex(NULL, 0, &TestThread, NULL, 0, 0);
cout << "After creating thread" << endl;
// ====================================
// Calling Calc routine through threads
// ====================================
HANDLE hnd2,
hnd3;
hnd2 = (HANDLE) _beginthreadex(NULL,
0,
&Thread,
(void *)&args[0],
0,
0);
hnd3 = (HANDLE) _beginthreadex(NULL,
0,
&Thread,
(void *)&args[1],
0,
0);
WaitForSingleObject(hnd1, INFINITE);
WaitForSingleObject(hnd2, INFINITE);
WaitForSingleObject(hnd3, INFINITE);
GetExitCodeThread(hnd1, &retval); // Gets the return value from the function
CloseHandle(hnd1);
CloseHandle(hnd2);
CloseHandle(hnd3);
return EXIT_SUCCESS;
}
The problem I am facing is when I execute the program I get the following output
Before creating new thread
After creating threadInside thread
Thu Aug 09 10:56:58 2012
Thu Aug 09 10:56:58 2012
C:\Documents and Settings\User\My Documents\Test Cases\1\1.datC:\Documents and Settings\User
\My Documents\Test Cases\2\2.dat
C:\Documents and Settings\kcomandur\My Documents\Test Cases\1\1.dboC:\Documents and Settings\User
\My Documents\Test Cases\2\2.dbo
The value of i inside the thread = 10000
Thu Aug 09 10:57:08 2012
and then program crashes. I get the following error
Debug Error!
Program: ...MultiThreading.exe
R6010
-abort() has been called
(Press Retry to debug the application)
When I do a retry, the break occurs in the generated .tli file in the following location starting with _com_dispatch_method
#pragma implementation_key(723)
inline IDispatch * IHeatExchangerNetwork::LoadHeatTransferUnit ( BSTR filename, enum HxUnitTypeKey unitType ) {
IDispatch * _result = 0;
_com_dispatch_method(this, 0x20, DISPATCH_METHOD, VT_DISPATCH, (void*)&_result,
L"\x0008\x0003", filename, unitType);
return _result;
}
The filename variable has the value
C:\Documents and Settings\User\My Documents\Test Cases\2\2.dat
I tried using mutex and modified the Thread function
unsigned int __stdcall Thread(void *args)
{
CoInitialize(0);
{
WaitForSingleObject(th_mutex, INFINITE);
// Same content as original Thread function.
// Not writing it again to minimize space
ReleaseMutex(th_mutex);
}
CoUninitialize();
return EXIT_SUCCESS;
}
//____________________________________
This time the program crashes at the following location _com_dispatch_method in the .tli file
#pragma implementation_key(966)
inline long IHeatTransferUnit::WriteDBOFile ( BSTR filename, short io, const VARIANT & vAppend ) {
long _result = 0;
_com_dispatch_method(this, 0x32, DISPATCH_METHOD, VT_I4, (void*)&_result,
L"\x0008\x0002\x080c", filename, io, &vAppend);
return _result;
}
By using mutex the error is being generated by the thread which has the HANDLE hnd3. The variable filename has the value
C:\Documents and Settings\User\My Documents\Test Cases\2\2.dbo
Also by using mutex I was able to get past the previous error location.
I am not sure if I really need a mutex as the following call
hxNetwork->Run(0, 0);
works on two different files that are no way related to each other. Also this is the most time consuming portion of the program and hence I wanted to run 2 cases simultaneously.
By using mutex the way I did, it runs the first case and then the second case.
Also the I have no control over the calc.dll. It is a third part software and I am not sure if supports multithreading or not.
So I would like to know what I need to do to get both the runs going and also be able to output the 2 files
Thanks in advance