Whether the user needs to determine the status of span to reduce the consumption caused by tracking!

[AtlanCI]

When marked as not sampled

Should I use a method like SpanFromContex().IsValid() in my application to return quickly to reduce the consumption of tracing. My span has only a few additions. All attachments are no more than 15 in total (including Attribute, event, link, resouce)

When TraceProvider is not set

What happens in this case?

example

[dmathieu]

this is the default tracer provider. If no configuration has happened, the interface will still be working, but under that noop tracer provider.
So no, you shouldn't have to perform this kind of check every time you need to start a new span.

If you want to check by yourself, you should run your own benchmark tests though.

[AtlanCI]

I see that span and accompanying resources are still generated when marked as unsampled. Does that mean I need to check when unsampled.

Also when tracerProvider is not set, if the application has some properties for assembling additional resources it will also execute.

[AtlanCI]

Do you have any good ideas or suggestions based on the above? @dmathieu

[dmathieu]

Yes, there is going to be some cost to generating a span which is then never processed. But the biggest cost should be to actually process the span, not to generate it.
You can add checks for span.IsRecording() everywhere in your code, but that's also at the expense of readability.

My recommendation would be for you to run your own benchmark tests with and without those conditions.
But I think you'll see that the cost is negligible.

[AtlanCI]

span.IsRecording() and isVaild() and isSample() Do they have any difference? In noop

[dmathieu]

span.SpanContext.IsValid checks that the current trace and span IDs are valid:

opentelemetry-go/trace/trace.go

Line 217 in 1f5b159

func (sc SpanContext) IsValid() bool {

span.SpanContext.IsSampled checks whethere the span state has the sample flag (coming from the propagator):

opentelemetry-go/trace/trace.go

Line 285 in 1f5b159

func (sc SpanContext) IsSampled() bool {

span.IsRecording returns true if the span is recording (and if it's not finished).
A recording span: https://github.com/open-telemetry/opentelemetry-go/blob/main/sdk/trace/span.go#L172
A non-recording span: https://github.com/open-telemetry/opentelemetry-go/blob/main/trace/noop.go#L65

With head-based sampling, you may get non-recording spans.
With tail-based sampling, all your spans will be recording, since the sampling decision happens just before export.

[AtlanCI]

Sampling decisions are not determined at the time of production span?
What happens when I create a span directly and determine its IsSample?

ctx,span := trace.Start(xx,xx,xx)
trace.IsSample() // return ?

[dmathieu]

The internal sampling mechanism is head-based. So yes, sampling decision is determined when the span is created.
See https://github.com/open-telemetry/opentelemetry-go/blob/main/sdk/trace/tracer.go#L90

[AtlanCI]

What about the sampling mechanism as shown below?

[dmathieu]

Samplers define a ShouldSample method, which makes the sampling decision. That method is called at the exact line linked in my previous comment :)

[AtlanCI]

okay, I look. very thanks