Http.HttpRequestOut OpenTelemetry spans not finished if filtered

[jamescrosswell]

Problem

For background context see:

• High memory usage with OpenTelemetry integration #3166 (reply in thread)

If OpenTelemetry is configured with filtering - e.g. as follows:

AddHttpClientInstrumentation(o => o.FilterHttpRequestMessage = _ => false)

... then our SentrySpanProcessor receives OnStart events for any outgoing requests from HttpClient but never receives a corresponding OnEnd event.

This leaves a bunch of SentrySpan instances accumulating in SpanProcessor._map, which never get cleaned up.

Investigation

• Created a discussion in the OpenTelemetry repo