Question

我编写了下一个代码来防止通过MUTEX实现多实例化，但是我想通过允许设置允许实例的最大数量来扩展其功能，所以我应该决定是否要仅允许单个实例或仅包含3个实例的多实例（例如）。

我试图弄清楚如何计算进程的互斥量，但我没有找到任何关于。

另一方面，我在StackOverflow中发现了很多帖子，解释了如何通过它的文件名来计算进程数量，我对此没有兴趣，因为我选择了 MUTEX < / strong>检测对我来说更安全。

有人可以随心所欲地帮助我吗？。

这就是我所做的一切：

Namespace My Partial Friend Class MyApplication #Region " Properties " ''' <summary> ''' Gets the current process mutex identifier. ''' </summary> ''' <value>The current process mutex identifier.</value> ''' <exception cref="System.FormatException">The specified value is not a valid GUID format.</exception> Private ReadOnly Property MutexID As String Get ' Define a Golabl Unique Identifier to name the Mutex. Dim Id As String = "b045ce40-2863-4ce7-a7df-8afca8214454" If Guid.TryParse(input:=Id, result:=New Guid) Then Return Id Else Throw New FormatException("The specified value is not in a valid GUID format.") End If End Get End Property ''' <summary> ''' Gets the maximum instances allowed for this process. ''' </summary> ''' <value>The maximum instances allowed for this process.</value> Private ReadOnly Property MaxInstances As Integer Get Return 2 End Get End Property #End Region #Region " Private Methods " ''' <summary> ''' Determines whether this is the unique instance that is running for this process. ''' </summary> ''' <returns><c>true</c> if this is the unique instance; otherwise, <c>false</c>.</returns> Private Function IsUniqueInstance() As Boolean Dim mtx As Threading.Mutex = Nothing Try mtx = Threading.Mutex.OpenExisting(name:=Me.MutexID) mtx.Close() mtx = Nothing Catch mtx = New Threading.Mutex(initiallyOwned:=True, name:=Me.MutexID) End Try Return mtx IsNot Nothing End Function #End Region #Region " Event-Handlers " ''' <summary> ''' This occurs when the application starts, before the startup Form is created. ''' </summary> ''' <param name="sender">The source of the event.</param> ''' <param name="e">The <see cref="ApplicationServices.StartupEventArgs"/> instance containing the event data.</param> Private Sub MyApplication_Startup(ByVal sender As Object, ByVal e As ApplicationServices.StartupEventArgs) _ Handles Me.Startup ' If there is more than one instance running of this process with the same mutex then... If Not Me.IsUniqueInstance Then ' Prevent multi-instancing. MessageBox.Show("This is a limited demo, to run multiple instances please purchase the program.", Application.Info.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Error) ' Cancel the application execution. e.Cancel = True End If End Sub #End Region End Class ' MyApplication End Namespace

更新

这是我正在尝试的代码，我在应用程序事件，表单构造函数，加载和显示事件中尝试过，但是没有检测到多个实例。

Private Sub test() Handles Me.Startup Using semaphore As New Semaphore(3I, 3I, "something") If Not semaphore.WaitOne(100I) Then MsgBox("Already max instances running") End Else MsgBox("test") End If End Using End Sub

Answer 1

Mutex是互斥的。它最多只允许一个线程继续进行。如果您需要允许线程数（在这种情况下为处理），则需要Semaphore而不是互斥。

C＃样本：

private static void Main()
{
    using (Semaphore semaphore = new Semaphore(3, 3, Assembly.GetExecutingAssembly().GetName().FullName))
    {
        if (!semaphore.WaitOne(100))
        {
            MessageBox.Show("Already max instances running");
            return;
        }

        //Start your application here
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
    }
}

VB.Net示例：

Private Shared Sub Main()
    Using semaphore As New Semaphore(3, 3, Assembly.GetExecutingAssembly().GetName().FullName)
        If Not semaphore.WaitOne(100) Then
            MessageBox.Show("Already max instances running")
            Return
        End If

       'Start your application here
        Application.EnableVisualStyles()
        Application.SetCompatibleTextRenderingDefault(False)
        Application.Run(New Form1())
    End Using
End Sub

P.S：使用http://converter.telerik.com/从C＃转换为VB

的代码

通过计算互斥量的数量来限制最大流程实例？

1 个答案: