ReleaseMutex function

Releases ownership of the specified mutex object.

Syntax

BOOL ReleaseMutex(
  HANDLE hMutex
);

Parameters

hMutex

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

Return Value

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 obtains ownership of a mutex either by creating it with the bInitialOwner parameter set to TRUE or by specifying its handle in a call to one of the wait functions. When the thread no longer needs to own the mutex object, it calls the ReleaseMutex function so that another thread can acquire ownership.

A thread can specify a mutex that it already owns in a call to one of the wait functions 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 one time for each time that it obtained ownership (either through CreateMutex or a wait function).

Examples

For an example that uses ReleaseMutex, see Using Mutex Objects.

Requirements

   
Windows version Windows XP [desktop apps | UWP apps] Windows Server 2003 [desktop apps | UWP apps]
Target Platform Windows
Header synchapi.h (include Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008 Windows Server 2008 R2, Windows.h)
Library Kernel32.lib
DLL Kernel32.dll

See Also

CreateMutex

Mutex Objects

Synchronization Functions