tRPC middleware spans include spans from unrelated tRPC endpoints

[jonathanj]

My Sentry distributed tracing view shows me that my tRPC procedure foo called the foo endpoint on an internal upstream service, however it also seems to indicate that foo also called the bar endpoint on that internal upstream service. Which is not possible because the foo implementation does not call bar, and neither does the upstream service call bar for any other reason.

I suspect this is because tRPC's httpBatch link bundles several client request into a single HTTP request, which are then unbundled by tRPC and the individual procedures called. The Sentry tRPC middleware looks as though it should create a separate span for each tRPC procedure, and this should never happen?

Am I misunderstanding something? Would passing the forceTransaction option to createSpan in the middleware solve this?

[lforst]

Hi, would you mind sharing an example (event in sentry) of this? Also what SDK version are you on?

I believe middlewares are invoked separately for each procedure - even if they come in bundled as one. On v7 we may have a bug in regards to this, since the behaviour back then was to override the name of the current running transaction, which would be a race condition.

[jonathanj]

Hi Luca,

Sorry for not providing a concrete example, I didn't want to share a screenshot publicly.

Anyway, I was digging into this after my post and I'm sure that I was running into exactly the bug you mentioned. I didn't realise that the implementation I was reading on Github was for 8.x initially, went to look at the 7.x implementation, and realised what was happening.

I'm unable to upgrade for other reasons, but I did backport the trpcMiddleware from 8.x and it solved my issue!

[lforst]

Awesome, glad to hear! Sorry that you had ran into issues previously. I have to admit, I did not even know of this bug in v7 until you posted this discussion. In hindsight, it is obvious.