C# - Debug.WriteLine - is this function ASync?

Question

Hello;

I just came across a situation: I was debugging a thread which iterates through a large amount of data. I was using Debug.WriteLine to print which record is being processed. What just happened is that thread has reported that it has processed all records, however, Visual Studio's debug window is still displaying out. I am positive that thread has completed its job.

Is Debug.WriteLine Async or data has been stacked in Visual Studio's buffer and is getting displayed slowly?

Answer 1

Visual Studio is doing the async part. The Win32 API OutputDebugString does the same thing in Visual Studio's output window.

You could try using DebugView instead.

Answer 2

Hi, MS does not mention this method as being async. The Debug.WriteLine method operates on the trace listeners and the phenomena you are seeing is a result of the implementation of the trace listener and not the Debug.WriteLine.

In general output is flushed to the screen when a buffer is full or after a timeout and not as it happens. This means that you should expect the output to be synchronous but delayed.