Which trace source is used by System.Diagnostics.Trace.WriteLine?

Question

As far as I can see, there are two ways to create trace messages in .NET.

1. The static methods of System.Diagnostics.Trace:

   Trace.WriteLine("Something happened");
   

2. The instance methods of System.Diagnostics.TraceSource:

   var ts = new TraceSource("TraceTest");
   ts.TraceInformation("Something happened");
   

In my app.config file, I can either add a trace listener for everything:

<system.diagnostics>
    <trace>
        <listeners>
            ...
        </listeners>
    </trace>
</system.diagnostics>

or for one particular trace source:

<system.diagnostics>
    <sources>
        <source name="...">
            <listeners>
                ...
            </listeners>
        </source>
    </sources>
</system.diagnostics>

My question

If I use the first method (static methods of System.Diagnostics.Trace), which trace source name is used?

_{I've checked the MSDN page of System.Diagnostics.Trace, but did not find the answer there.}

Answer 1

I checked the source of Trace.Writeline with JustDecompile and it enums all listeners and sends the message to all:

                foreach (TraceListener listener in TraceInternal.Listeners)
                {
                    if (listener.IsThreadSafe)
                    {
                        listener.WriteLine(message);
                        if (!TraceInternal.AutoFlush)
                        {
                            continue;
                        }
                        listener.Flush();
                    }
                    else
                    {
                        lock (listener)
                        {
                            listener.WriteLine(message);
                            if (TraceInternal.AutoFlush)
                            {
                                listener.Flush();
                            }
                        }
                    }
                }

But forget this ugly Trace calls, use ETW Eventsource for a much better tracing/logging