None.

The threads of a single process can use a critical section object for mutual-exclusion synchronization. The process is responsible for allocating the memory used by a critical section object, which it can do by declaring a variable of type CRITICAL_SECTION. Before using a critical section, some thread of the process must call the InitializeCriticalSectionto initialize the object.

To enable mutually exclusive access to a shared resource, each thread calls the EnterCriticalSectionfunction to request ownership of the critical section before executing any section of code that accesses the protected resource. EnterCriticalSectionblocks until the thread can take ownership of the critical section. When it has finished executing the protected code, the thread uses the LeaveCriticalSectionfunction to relinquish ownership, enabling another thread to become owner and access the protected resource. The thread must call LeaveCriticalSectiononce for each time that it entered the critical section. The thread enters the critical section each time EnterCriticalSectionsucceeds.

After a thread has ownership of a critical section, it can make additional calls to EnterCriticalSectionwithout blocking its execution. This prevents a thread from deadlocking itself while waiting for a critical section that it already owns.

Any thread of the process can use the DeleteCriticalSectionfunction to release the system resources that were allocated when the critical section object was initialized. After this function has been called, the critical section object can no longer be used for synchronization.

If a thread terminates while it has ownership of a critical section, the state of the critical section is undefined.

If a critical section is deleted while it is still owned, the state of the threads waiting for ownership of the deleted critical section is undefined.

If multiple threads call EnterCriticalSection, and the critical section is currently owned by a different thread, the highest priority thread among the calling threads gets the critical section first after the current thread leaves the critical section. If all the calling threads have the same priority, a first-in, first-out (FIFO) basis is used after the current thread leaves the critical section.

Each object type, such as memory maps, semaphores, events, message queues, mutexes, and watchdog timers, has its own separate namespace. Empty strings, "", are handled as named objects. On Windows desktop-based platforms, synchronization objects all share the same namespace.