What is guaranteed on a completed Activity?

[erwinkramer]

Lets say i build a console app with the .NET implementation of OTel, and i use a simple processor. What guarantees do i get in terms of delivery of traces/requests when i create a using block with an Activity and some logs i sent with the ILogger interface. In other words, if it has successfully passed one Activity (disposed it) without issues:

1. Can it still be somewhere in offline store? https://learn.microsoft.com/en-us/azure/azure-monitor/app/opentelemetry-configuration?tabs=net#offline-storage-and-automatic-retries - if so, what if i restart the console app, would it recover and get missed traces and activities from offline storage and send it again?
2. Can it still be in an OTel Processor, without being in offline storage? - if so, if i restart the console app, it most likely won't recover the missed traces and activities?
3. Is it only guaranteed when disposing the logger factory and/or trace provider? Or is it still not guaranteed when disposing both of those, and can it still be somewhere halfway (see 1 and 2)?
4. Could Add ForceFlush to the TracerProvider Trace API specification opentelemetry-specification#2944 guarantee it?

Ideally i want to see an Activity as an actual transaction, so if it's done, i can get over with it and i know it's delivered and registered, or at least at a place where it's easily being retried (see 1) when starting up the app again. Basically, think about some disaster like out of memory or power outage, i would like to know which activity actually survived.

[erwinkramer]

I think i answered my own question via https://github.com/erwinkramer/otel-business?tab=readme-ov-file#reliability-notes and proved it via this test: https://github.com/erwinkramer/otel-business/blob/main/IntegrationTest/Tests.cs

• all logs using ILogger with default settings doesn't guarantee anything
• using an Activity doesn't guarantee anything. Only when you specify ForceFlush you have the guarantee that (only) spans (which are completed) and related span events (via ActivityEvent) are sent out.