ReleaseMutex

The ReleaseMutex function releases ownership of the specified mutex object.

BOOL ReleaseMutex(
  HANDLE hMutex   // handle to mutex object
);
 

Parameters

hMutex
Handle to the mutex object. The CreateMutex or OpenMutex function returns this handle.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

The ReleaseMutex function fails if the calling thread does not own the mutex object.

A thread gets ownership of a mutex by specifying a handle to the mutex in one of the wait functions. The thread that creates a mutex object can also get immediate ownership without using one of the wait functions. When the owning thread no longer needs to own the mutex object, it calls the ReleaseMutex function.

While a thread has ownership of a mutex, it can specify the same mutex in additional wait-function calls without blocking its execution. This prevents a thread from deadlocking itself while waiting for a mutex that it already owns. However, to release its ownership, the thread must call ReleaseMutex once for each time that the mutex satisfied a wait.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Requires version 1.0 or later.
  Header: Declared in winbase.h.
  Import Library: Use kernel32.lib.

See Also

Synchronization Overview, Synchronization Functions, CreateMutex