When debugging netcoreapp2.0 in VS, http dependencies are tracked twice

[lmolkova]

HttpClient in 2.0 fires deprecated and 'new' events.

When debugging, VS subscribes to deprecated events, AppInsights subscribes to 'new' events from 2.0 client (but also listens to old events to support older versions).

AppInsights attempts to filter out old events for 2.0 clients (https://github.com/Microsoft/ApplicationInsights-dotnet-server/blob/develop/Src/DependencyCollector/Shared/Implementation/HttpCoreDiagnosticSourceListener.cs#L560) with IsEnabled callback.
However when there are 2 listeners for diagnostics source, it's enough if just one of them returns true for IsEnabled, then all listeners get the notification.

So, isNetCore20HttpClient check should be done in OnRequest and OnResponse callbacks too.

[SergeyKanzhelev]

So you receive every http call twice?

[lmolkova]

@SergeyKanzhelev @Dmitry-Matveev @zakimaksyutov @cijothomas how far are you guys from releasing 2.5? Could we include the fix for it? Should be pretty straightforward and small fix.

[lmolkova]

@SergeyKanzhelev exactly, all http calls are tracked twice when debugging in VS

[Dmitry-Matveev]

@lmolkova , 2.5-Beta1 is around the corner. 2.5 stable was initially planned for this quarter, but no certain date yet. 2.5-Beta2 is the closest and was planned for November.

[lmolkova]

#848