在C，多线程，多窗口调用一个窗口过程，每个调用将使用新的局部变量或我需要一个互斥？

Question

I tried to explain it all in the title: I have a multithreaded C program which will have multiple windows calling one Window Procedure.

There is some processing done in the window procedure. Do I need to protect it, or will each call to the window procedure be separated in memory?

My instinct is that I don't need a mutex, because they're all local variables, is this wrong?

LRESULT APIENTRY EditSubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) 
{   
    if (uMsg == WM_GETDLGCODE) 
        return DLGC_WANTALLKEYS;
    else if(uMsg == WM_CHAR)
    {
        if( (int) wParam == 13)
        {
            char* strCurrentCommand;

            unsigned long ulThisConversation = GetConversation(0, 0, hwnd, 0, 0);
            ...

I'm concerned with the local variables strCurrentCommand and ulThisConversation.

Answer 1

Local variables and parameters to functions go on the stack. Each thread gets its own stack, and each invocation of a function gets a space on the stack of the thread it's running in for its parameters and local variables. So you're fine.

Answer 2

您不需要使用互斥锁保护堆栈变量。

Answer 3

No need to protect local variables, as each call to the window proc function will allocate new copies on the stack.

But keep in mind that to avoid the need for a mutex or other synchronization mechanisms you also need to make sure any functions called from inside your window proc function (like GetConversation and any functions this function calls) are thread safe.