Why does Debug.Writeline stop working for some projects in the solution?

visual-studio-2010

Solution

After being tormented by this for years I finally found the cause and the solution in this Stack Overflow question: vs2010 Debug.WriteLine stops working

It seems that Visual Studio's handinlg of debug.writeline can't handle multiple processeses that each use multiple threads correctly. Eventually the 2 processes will deadlock the portion of visual studio that handles the output, causing it to stop working.

The solution is to wrap your calls to debug.writeline in a class that synchronizes across processes using a named mutex. This prevents multiple processes from writing to debug at the same time, nicely side stepping the whole deadlock problem.

The wrapper:

public class Debug
{
     #if DEBUG
         private static readonly Mutex DebugMutex =new Mutex(false,@"Global\DebugMutex");
     #endif

     [Conditional("DEBUG")]
     public static void WriteLine(string message)
     {
         DebugMutex.WaitOne();
         System.Diagnostics.Debug.WriteLine(message);
         DebugMutex.ReleaseMutex();
     }

     [Conditional("DEBUG")]
     public static void WriteLine(string message, string category)
     {
         DebugMutex.WaitOne();
         System.Diagnostics.Debug.WriteLine(message,category);
         DebugMutex.ReleaseMutex();
     }
}

Or for those using VB.NET:

Imports System.Threading

Public Class Debug
#If DEBUG Then
  Private Shared ReadOnly DebugMutex As New Mutex(False, "Global\DebugMutex")
#End If

<Conditional("DEBUG")> _
Public Shared Sub WriteLine(message As String)
    DebugMutex.WaitOne()
    System.Diagnostics.Debug.WriteLine(message)
    DebugMutex.ReleaseMutex()
End Sub

<Conditional("DEBUG")> _
Public Shared Sub WriteLine(message As String, category As String)
    DebugMutex.WaitOne()
    System.Diagnostics.Debug.WriteLine(message, category)
    DebugMutex.ReleaseMutex()
End Sub
End Class

Problem

Original source