title: What happens if the callback method takes more than the specified Timer's time period?
body: <p>I have the below code. What happens if the Upload method takes more than one minute for completion? Does the timer kick off another call to the Upload method immediately after one minute is over or Does it wait until the method finishes executing? I am implementing this as a windows service. </p>
  
  <pre><code>Protected Overrides Sub OnStart(ByVal args() As String)    
    Dim tmr As Timer = New Timer(New TimerCallback(AddressOf Upload), Nothing, 1000, **60000**)
  
    While Not tmr Is Nothing
    End While
  End Sub
  
  Public Sub Upload(ByVal o As Object)
    Dim sr As StreamReader
    ..........
    ..........
  End Sub
  </code></pre>