How to Ensure Only One Instance of a Go Application Runs System-Wide Using a Global Mutex?

Restricting to Single Instance of Golang Executable with Global Mutex

It's a common requirement to enforce a single instance of an application. Golang provides a convenient solution using the sync.Mutex package. However, this method only works within a single process. To restrict the application to a single instance across the system, leveraging a global mutex is necessary.

On Windows, the kernel32.dll library offers the CreateMutexW function to create a system-wide mutex. This function requires a unique name for the mutex to identify it across processes.

Example:

var (
    kernel32        = syscall.NewLazyDLL("kernel32.dll")
    procCreateMutex = kernel32.NewProc("CreateMutexW")
)

func CreateMutex(name string) (uintptr, error) {
    ret, _, err := procCreateMutex.Call(
        0,
        0,
        uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(name))),
    )
    switch int(err.(syscall.Errno)) {
    case 0:
        return ret, nil
    default:
        return ret, err
    }
}

// mutexName starting with "Global\" will work across all user sessions
_, err := CreateMutex("SomeMutexName")

By specifying a name starting with "Global" in CreateMutex, the mutex can be accessed across multiple user sessions. This ensures that only a single instance of the application is running on the system.

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