Why does this simple .NET console app have so many threads?

Question

This simple program starts with 15 threads - according to the count. Sometimes during its lifetime it drops a few, but they come back.

class Program  {      static void Main(string[] args)      {          while (true)          {              Console.WriteLine(Process.GetCurrentProcess().Threads.Count);              Thread.Sleep(500);          }      }  } 

I was expecting the process to just have one thread (and my intuition was backed up by this)

Without the debugger, the process has only (!) 4 threads. Surely any CLR stuff would be hidden from my process?

What count is this? Does the process really have that many threads? Why?

Answer 1

Try running it outside the debugger (i.e. press Ctrl+F5 instead of F5). You should only see three threads - the main thread, the GC thread & the finalizer thread IIRC. The other threads you see are debugger-related threads.

Answer 2

Project + Properties, Debugging, untick "Enable the Visual Studio hosting process". I can't discover what it is doing. As soon as I tick the "Enabled unmanaged code debugging" option to try to get a peek at these threads, they no longer get started. No clue. But I'm sure it's for our benefit :)