[EventListener] Include thread ID

[kouvel]

EventWrittenEventArgs doesn't appear to provide information about which thread fired the event. It would be useful to have that information to be able to associate paired events such as Start/Stop that may be fired from multiple threads concurrently.

As for which thread ID, it would be useful to have both the OS thread ID, and the managed thread ID if it's a managed thread. The OS thread ID would be useful for events fired by the runtime, some of which may be fired from unmanaged threads. The managed thread ID would be useful for consumers tracking their events that are fired from managed threads using .NET APIs.

[stephentoub]

Isn't the EventSource event fired synchronously, in which case you can just look at Environment.CurrentManagedThreadId?

[kouvel]

The callback is happening on a thread pool thread and it's a different thread from the thread that fired the event (main thread in this case).

   at System.Environment.get_StackTrace()
   at TieringInProcEventListener.ClrEventListener.OnEventWritten(EventWrittenEventArgs eventData) in D:\Test\source\test\Program.cs:line 65
   at System.Diagnostics.Tracing.EventSource.DispatchToAllListeners(Int32 eventId, Guid* childActivityID, EventWrittenEventArgs eventCallbackArgs)
   at System.Diagnostics.Tracing.EventPipeEventDispatcher.DispatchEventsToEventListeners()
   at System.Threading.Tasks.Task.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   at System.Threading.Tasks.Task.ExecuteEntryUnsafe(Thread threadPoolThread)
   at System.Threading.Tasks.ThreadPoolTaskScheduler.<>c.<.cctor>b__10_0(Object s)
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart(Object obj)

[stephentoub]

Ah, EventPipe is doing the offloading.

[kouvel]

Updated description to specify the kind of thread ID