Question

This code runs successfully and MQStruct constructor initialized the values as well, I can see in ExecuteThread function but in TestFunction, I get the garbage values for MQStruct.

I am passing address of struct “&MQStructObj” to _beginthreadex for parameters and This is the problem I guess

struct MQStruct {
    MQStruct()
    {
        pointer=NULL;
        serviceName=NULL;
        durability=0;
        msgType=0;
        msgHeader=0;
        msgId=NULL;
        payload=NULL;
        payloadSize=0;
        ttl=0;
        priority=0;
    }

    void* pointer;
    wchar_t *serviceName; 
    int durability; 
    int msgType; 
    int msgHeader; 
    wchar_t *msgId; 
    wchar_t *payload; 
    int payloadSize; 
    int ttl; 
    int priority;
};


int ExecuteThread() {

    HANDLE   heartBeatThread;
    unsigned int hbThreadID;
    int result = 0;

        MQStruct MQStructObj;
        MQStructObj.pointer=this;

    heartBeatThread = (HANDLE)_beginthreadex(NULL, 0 , &TestFunction, &MQStructObj, 0/*CREATE_SUSPENDED*/, &hbThreadID);


    if ( heartBeatThread == 0 )
    {
        result = -1;
        LogEvent(DEBUG_LOG,0, "Fail to create thread");
    }


    CloseHandle(heartBeatThread);

    return result;
}

Answer 1

You guessed correctly.

You’re passing the address of a local variable to your thread-proc-startup, then leaving scope (and destroying the object in the process). References to this object in your thread proc are there-after undefined behavior.

Dynamically allocate one with new and let the thread proc delete it.