I've read several posts and articles on Critical Sections and Mutex but i'm not sure how to go about useing them.

Most of the things i've read show another class wrapping a CRITICAL_SECTION object or a mutex object? Why is that?

I have a MFC dialog applicaiton and a direct rendering window. The MFC DLG class starts a new thread like so:

static unsigned long __stdcall StartRenderer(void * Renderer) {
((classA *)Renderer)->update();
return 0;

unsigned long id;
m_RenderThread = CreateThread(NULL, 4 * 1024 * 1024, StartRenderer, (void *)&m_Render, 0, &id);
AssertVerify(SetThreadPriority(m_RenderThread,THREAD_PRIORITY_HIGHEST));
}

So this starts another thread and the function update is now running on that thread. This update function is in classA...

In this update() function i acess some data like stl maps and strings that are also accessed from other funcitons in class A that get called and are running on the main thread.

After reading up on the issue i think the best solution would be to use Critical Sections. I'd call EnterCriticalSection on any function that is going to be touching data that needs to be shared and LeaveCriticalSection at the end of the functions.

I pretty much already tried doing this only with bools. Any function running on the main thread i'd set a bool at the start and bool at the end. and wouldn't go into a function running on the other thread to enter if the bool was set.. Still getting crashes trying this

So i'm not exactly sure how to set up the Critical Section. Where would i have to delcare and init the CRITICAL_SECTION so both threads are able to know about it?