Refinery does not properly handle empty parentId strings when determining root spans

[julialamenza]

The Refinery considers a span to not be a root if the parentId is a string, but it doesn't check if the string is empty. This can lead to incorrect identification of root spans.
https://github.com/honeycombio/refinery/blob/main/collect/collect.go#L604
lso this will cause delays on the span being transmitted, because Refinery will wait for the parent span to show up, for TraceTimeout (60s by default). And in this case it never will, so any of these real rootspans are actually delayed by 60s for sending to Honeycomb.

Steps to Reproduce:

1. Create a span with an empty string as the parentId.
2. Observe that the span is not considered a root, even though it should be.

Expected Behavior:

Spans with an empty parentId string should be considered root spans.

• Refinery version: v2.6.1
• Operating system: Linux

[MikeGoldsmith]

Thanks for reporting the issue @julialamenza.

Can you describe the situation where you're seeing a span with an empty parentId? We'll look into considering empty values when determining whether a span is root.

[julialamenza]

Sometimes we are sending traces with trace.parent_id as a blank string and these appear to be "paused" in Refinery until the TraceTimeout elapses (as if it considered a blank string as a valid span_id).
As a result, the graphs for the service that sends these traces that way is delayed by 60s (the value of the TraceTimeout) and metrics look like they are dropping even though the traces are only delayed.
This seems to be a change in behaviour compared to Refinery 1.x

[kentquirk]

Are you using an OpenTelemetry library? If so, can you tell us which one? We can look into enabling this behavior, but it's counter to the OpenTelemetry specification.

[julialamenza]

No we dont

[MikeGoldsmith]

@julialamenza we've merged a fix and expect it to go out with our next release, likely in the next week or two.