TextWriterTraceListener not working as expected when adding to System.Diagnostics.Debug.Listeners

Full Program:

Option Strict On : Option Explicit On Module Module1

    Sub Mai开发者_StackOverflow社区n()
        'System.Diagnostics.Debug.Listeners.Add(New System.Diagnostics.TextWriterTraceListener("C:\a.txt"))
        System.Diagnostics.Debug.Listeners.Add(New System.Diagnostics.TextWriterTraceListener("a.txt"))
        System.Diagnostics.Debug.WriteLine("asd")
    End Sub

End Module

After I ran it, I had a file a.txt in my debug folder but the size is 0 bytes (and when i open it is empty of course)

Shouldn't the output had "asd" in it ?

Add one or more

 System.Diagnostics.Debug.Flush()

statements, and/or a

 System.Diagnostics.Debug.Close()

when closing that App.

I have found this issue also a long time ago. You can get around flushing every time if you are willing to use a CriticalFinalizer.