vb.net - 远程处理 : No answer from server but still works right after

Question

我有一个 VB.Net 应用程序，我通过 Remoting 创建了一些对象。

有时(并非总是)远程对象的创建会阻塞并且应用程序会卡住而不会抛出任何异常，即使服务器正常也是如此。我试图让它运行，但 15 分钟后，仍然没有任何反应。但是，如果我停止该应用程序并立即重新运行它，它就会完美运行。

有没有办法知道这有什么问题？或者在超时后重新创建远程对象的方法？

这是我用来创建远程对象的代码:

URL = "tcp://" & ServerIPAddress.ToString & ":" & ServerRemotingPort.ToString & "/TechnicalDatabase"
RemoteObject = CType(Activator.GetObject(GetType(TechnicalDatabase.TechnicalDatabaseObject), URL), TechnicalDatabase.TechnicalDatabaseObject)

这个问题大约每 10 次发生一次。

Answer 1

以下代码将被视为示例/简单修复。它没有解释“为什么”。它在 BackgroundWorker 中运行代码并使用 Timer 超时/中止 worker。

Imports System.Runtime.Remoting
Imports System.ComponentModel
Imports System.Threading.Thread

Public Class Form1

    Public Sub New()
        Me.InitializeComponent()
        Me.bgWorker = New BackgroundWorker()
        Me.bgWorker.WorkerSupportsCancellation = True
        Me.bgTimer = New System.Windows.Forms.Timer
        Me.bgTimer.Interval = 60000 '<-- Timeout after 1 minute.
    End Sub

    Private Sub Connect(ipAddress As String, portNumber As Integer, db As String)
        If (Me.bgWorker.IsBusy) Then
            Throw New Exception("Worker is busy.")
        End If
        Dim [error] As Exception = Nothing
        Try
            AddHandler Me.bgTimer.Tick, New EventHandler(AddressOf Me.OnTimeout)
            AddHandler Me.bgWorker.DoWork, New DoWorkEventHandler(AddressOf Me.OnDoWork)
            AddHandler Me.bgWorker.RunWorkerCompleted, New RunWorkerCompletedEventHandler(AddressOf Me.OnWorkCompleted)
            Me.bgTimer.Enabled = True
            Me.bgWorker.RunWorkerAsync(String.Format("tcp://{0}:{1}/{2}", ipAddress, portNumber, db))
        Catch ex As Exception
            [error] = ex
            Me.bgTimer.Enabled = False
            RemoveHandler Me.bgTimer.Tick, New EventHandler(AddressOf Me.OnTimeout)
            RemoveHandler Me.bgWorker.DoWork, New DoWorkEventHandler(AddressOf Me.OnDoWork)
            RemoveHandler Me.bgWorker.RunWorkerCompleted, New RunWorkerCompletedEventHandler(AddressOf Me.OnWorkCompleted)
        End Try
        If (Not [error] Is Nothing) Then
            Throw [error]
        End If
    End Sub

    Private Sub OnDoWork(sender As Object, e As DoWorkEventArgs)
        Me.bgThread = Thread.CurrentThread
        Try
            e.Result = CType(Activator.GetObject(GetType(TechnicalDatabase.TechnicalDatabaseObject), DirectCast(e.Argument, String)), TechnicalDatabase.TechnicalDatabaseObject)
        Catch ex As ThreadAbortException
            e.Cancel = True
            Thread.ResetAbort()
        Catch ex As Exception
            Throw ex
        End Try
    End Sub

    Private Sub OnWorkCompleted(sender As Object, e As RunWorkerCompletedEventArgs)
        Me.bgTimer.Enabled = False
        Me.bgThread = Nothing
        RemoveHandler Me.bgTimer.Tick, New EventHandler(AddressOf Me.OnTimeout)
        RemoveHandler Me.bgWorker.DoWork, New DoWorkEventHandler(AddressOf Me.OnDoWork)
        RemoveHandler Me.bgWorker.RunWorkerCompleted, New RunWorkerCompletedEventHandler(AddressOf Me.OnWorkCompleted)
        If (Not e.Error Is Nothing) Then
            MessageBox.Show(e.Error.Message, Me.Text, MessageBoxButtons.OK, MessageBoxIcon.Error)
        ElseIf (e.Cancelled) Then
            MessageBox.Show("Worker cancelled.", Me.Text, MessageBoxButtons.OK, MessageBoxIcon.Information)
        Else
            Dim remoteObject As Object = CType(e.Result, TechnicalDatabase.TechnicalDatabaseObject)
            MessageBox.Show("Success!", Me.Text, MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If
    End Sub

    Private Sub OnTimeout(sender As Object, e As EventArgs)
        Me.bgTimer.Enabled = False
        If (Not Me.bgThread Is Nothing) Then
            Me.bgThread.Abort()
        End If
    End Sub

    Private bgWorker As BackgroundWorker
    Private bgTimer As System.Windows.Forms.Timer
    Private bgThread As Thread

End Class

连接:

Me.Connect(ServerIPAddress.ToString(), ServerRemotingPort, "TechnicalDatabase")

灵感来源:

• How to “kill” background worker completely?
• Remoting timeout issues