[Stackdriver Trace] Cannot have multiple spans with the same name in a trace

[Adrian Bogatu]

Hi,

Situation: When sending a trace containing 2 spans (a root-span and a child span) that have the same span name, the two spans are merged together and only one span is displayed. In addition, some of the fields are overwritten and information is lost.

See example in the attachment (print screen from developer console in google cloud platform), where two spans both having the name "get_test" are sent in a trace to Stackdriver Trace: one client root-span and one server child span. The different annotations of both the spans are merged, but some shared annotations are overwritten by the client root-span (e.g. zipkin.io/span.kind is "client"). I expected to have 2 spans: one with the tag-value "client" and one "server".

This issue is because, I am guessing, the backend considers the span's uniqueness based on the span's name. I don't think that's correct, instead the unique span id should be used to track spans.

There are many cases when one wants to use the same name for multiple spans in a trace (e.g. span_name="get_users" to be the same for client and server; standard annotations in libraries like span_name="mysql-client" when you have multiple sequential MySQL request). In those cases, only one span with that specified name will exist, and annotations will be lost.

I used both a custom stackdriver trace client in Go (that uses Go package cloudtrace/v1) and the relatively new google's zipkin collector for stackdriver trace.

Thanks,

Adrian

[Nick (Cloud Platform Support)]

Hey Adrian,

Thanks for reporting this. I've just about reproduced this behaviour and will shortly post a link to a Public Issue Tracker thread you can follow for updates.

In general, posts like this, which look like a post that belongs in the Public Issue Tracker, should be posted there. This Google Groups forum is meant for more general and high level discussion of the App Engine platform and services rather than specific-issue technical reporting. We monitor there regularly and will quickly get the issue acknowledged and tracked.

I'll update this thread with a link to the thread once it's made, or if I need any further clarification on reproducing this behaviour.

Cheers,

Nick

Cloud Platform Community Support

[Adrian Bogatu]

Hi, Nick,

Thanks for the answer. Honestly, at first, I wanted to post on Google Code, but I know it has been discontinued in 2016 and I wasn't sure it was tracked anymore.

Thanks,
Adrian

[Nick (Cloud Platform Support)]

Hey Adrian,

While opening new projects on Google Code was discontinued, we continue to operate Public Issue Trackers for many of our projects there as the official forums for issue reporting, and we monitor them daily. Here are a few of them:

App Engine
Compute Engine
Cloud SDK
Cloud SQL

BigQuery
Cloud Platform

Cheers,

Nick
Cloud Platform Community Support

[Adrian Bogatu]

Are there any updates regarding this issue? Do you want me to post it directly to Google Code?

[Nick (Cloud Platform Support)]

Hey Adrian,

Not to worry, I ought to have updated here to let you know - we're working on diagnosing the issue and preparing an internal report for it, and will post a public issue tracker thread and link it here once we've got that squared away. Shouldn't be too much longer. Thanks for checking! In future, you can post directly there, but it's no problem for us to create a thread this way in this case.

Cheers,

Nick
Cloud Platform Community Support

[Nick (Cloud Platform Support)]

Hey Adrian,

We've reproduced this issue and you can track progress on it here in the google-cloud-platform  Public Issue Tracker.

Cheers,

Nick
Cloud Platform Community Support