Question

What data does the Win32 CRITICAL_SECTION contain, and how big is it?

This is undocumented and presumably implementation specific, but I’m curious to know

Answer 1

This is from my installation of Windows Vista SDK:

WinNT.h:

typedef struct _RTL_CRITICAL_SECTION {
    PRTL_CRITICAL_SECTION_DEBUG DebugInfo;

    //
    //  The following three fields control entering and exiting the critical
    //  section for the resource
    //

    LONG LockCount;
    LONG RecursionCount;
    HANDLE OwningThread;        // from the thread's ClientId->UniqueThread
    HANDLE LockSemaphore;
    ULONG_PTR SpinCount;        // force size on 64-bit systems when packed
} RTL_CRITICAL_SECTION, *PRTL_CRITICAL_SECTION;

WinBase.h:

typedef RTL_CRITICAL_SECTION CRITICAL_SECTION;