Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
563 views
in Technique[技术] by (71.8m points)

c# - How do I listen to TPL TaskStarted/TaskCompleted ETW events

I am interested in listening to ETW (event tracing for Windows) TPL events, in particular I'd like to know when a Task starts and when it stops.

Here's a sample program I've used for testing:

   using System;
   using System.Collections.Generic;
   using System.Diagnostics.Tracing;
   using System.Linq;
   using System.Text;
   using System.Threading;
   using System.Threading.Tasks;

   namespace ConsoleApplication10
   {
      class Listener : EventListener
      {
         private static readonly Guid tplGuid = new Guid("2e5dba47-a3d2-4d16-8ee0-6671ffdcd7b5");

         protected override void OnEventSourceCreated(EventSource eventSource)
         {
            Console.WriteLine("Got guid: " + eventSource.Guid);
            EnableEvents(eventSource, EventLevel.LogAlways);
         }

         protected override void OnEventWritten(EventWrittenEventArgs eventData)
         {
            Console.WriteLine("Event: " + eventData.EventId);
         }
      }

      class Program
      {
         static void Main(string[] args)
         {
            using (var listener = new Listener())
            {
               Action doIt = null;
               doIt = () =>
               {
                  Thread.Sleep(1000);
                  Console.Write('.');
                  Task.Run(doIt);
               };
               Task.Run(doIt);

               Parallel.Invoke(() => Console.WriteLine("invoke"));

               Console.Read();
            }
         }
      }
   }

Sample output is as follows on my machine:

Got guid: 8e9f5090-2d75-4d03-8a81-e5afbf85daf1
Got guid: 2e5dba47-a3d2-4d16-8ee0-6671ffdcd7b5
Event: 3
invoke
Event: 4
.......

So the Invoke method causes an event to fire, yet the Tasks fire none. Looking at the Task source (e.g. reference source) the code appears no different from how the Parallel.Invoke event fires.

What is wrong with the above, or, how do I listen to TaskStarted and TaskCompleted events (or any Task related event for that matter)?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Your question challanged me to look into ETW (which I've been wanting to look into for a while). I was able to capture "task start" and "task end" using Microsoft.Diagnostics.Tracing.TraceEvent NuGet library with the simple following code:

private static void Main(string[] args)
{
    Task.Run(() =>
    {
        using (var session = new TraceEventSession("TplCaptureSession"))
        {
            session.EnableProvider(new Guid("2e5dba47-a3d2-4d16-8ee0-6671ffdcd7b5"),
                                   TraceEventLevel.Always);

            session.Source.Dynamic.AddCallbackForProviderEvent("System.Threading.Tasks
                                                               .TplEventSource",
                "TaskExecute/Start", @event =>
                {
                    Console.WriteLine("Inside Task Started");
                });

            session.Source.Dynamic.AddCallbackForProviderEvent("System.Threading.Tasks
                                                   .TplEventSource", 
                "TaskExecute/Stop", @event =>
                {
                    Console.WriteLine("Inside Task Stopped");
                });

            session.Source.Process();
        }
    });

    var task = Task.Run(async () =>
    {
        await Task.Delay(20000);
    });

    task.Wait();
}

Basically what happens is:

  1. We start new a live event capturing session using TraceEventSession where we pass it TraceEventLevel.Always to print out all messages (we could narrow this down to TranceEventLevel.Information, but for the example I chose all).

  2. We enable the TplEventSource provider by passing its Guid to session.EnableProvider.

  3. We register a callback to be invoked once TplEventSource (which is the event source for TPL, obviously) fires either TaskExecute/Start or TaskExecute/Stop events (taken from the reference source)

  4. We print out once we're inside the event.

Note my use of Task.Run was simply because session.Source.Process() is a blocking call, and I wanted it to run in the background.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...