Getting debug error in multithreaded VS code and unable to find issue

Question

I keep getting a debug error thrown, telling me that abort() has been called and then when I go to debug in Visual Studio it takes me to the following code (the last line is where it throws):

void __cdecl _NMSG_WRITE (
        int rterrnum
        )
{
        const wchar_t * const error_text = _GET_RTERRMSG(rterrnum);

        if (error_text)
        {
            int msgshown = 0;
#ifdef _DEBUG
            /*
             * Report error.
             *
             * If _CRT_ERROR has _CRTDBG_REPORT_WNDW on, and user chooses
             * "Retry", call the debugger.
             *
             * Otherwise, continue execution.
             *
             */

            if (rterrnum != _RT_CRNL && rterrnum != _RT_BANNER && rterrnum != _RT_CRT_NOTINIT)
            {
                switch (_CrtDbgReportW(_CRT_ERROR, NULL, 0, NULL, L"%s", error_text))
                {
                case 1: _CrtDbgBreak(); msgshown = 1; break;

It appears when I step over whatever-is-the-last-line in the below function:

X::my_func(){

    //a,b,c are 2x ints and a unordered_map
    std::thread t1(&X::multi_thread_func, this, a, b, c);

    int c = 0;

    //The debug error message doesn't appear until I step over this line. If I were
    //to add further code to this function then the error only appears after stepping
    //over the last line in the function.
    int c1 = 0;
}

I appreciate there's not a lot to go on- but could people give me tips how I could continue my investigation from within Visual Studio 2012?

EDIT: If I remove the multithreaded call I don't get the error

Sam · Accepted Answer · 2013-11-18 01:09:41Z

1

A std::thread instance must either be joined or detached, before it can be destructed (what happens, as soon as t1 goes out of scope). Otherwise, the destructor of std::thread will call std::terminate(). This might be the cause of that abort.

X::my_func(){

    //a,b,c are 2x ints and a unordered_map
    std::thread t1(&X::multi_thread_func, this, a, b, c);
    t1.join();// <--- ... however, using a thread like this makes little to no sense.

    int c = 0;

    //The debug error message doesn't appear until I step over this line. If I were
    //to add further code to this function then the error only appears after stepping
    //over the last line in the function.
    int c1 = 0;
}

answered Nov 18, 2013 at 1:09

Sam

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2 Comments

user997112 Over a year ago

Hi Sam. The reason I don't join the thread in X::my_func() is because the function which called X::my_func() then calls X::my_func() again to create another thread (but passing in different parameters for the second thread to operate on).

Sam Over a year ago

In this case, you may return that thread instance, so that all created threads can be joined at some point.

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