[−][src]Module opentelemetry::api::trace::sampler
OpenTelemetry Sampler Interface
Sampling
Sampling is a mechanism to control the noise and overhead introduced by OpenTelemetry by reducing the number of samples of traces collected and sent to the backend.
Sampling may be implemented on different stages of a trace collection.
OpenTelemetry API defines a Sampler
interface that can be used at
instrumentation points by libraries to check the sampling SamplingDecision
early and
optimize the amount of telemetry that needs to be collected.
All other sampling algorithms may be implemented on SDK layer in exporters, or even out of process in Agent or Collector.
The OpenTelemetry API has two properties responsible for the data collection:
is_recording
method on aSpan
. Iftrue
the currentSpan
records tracing events (attributes, events, status, etc.), otherwise all tracing events are dropped. Users can use this property to determine if expensive trace events can be avoided.SpanProcessor
s will receive all spans with this flag set. However,SpanExporter
s will not receive them unless theSampled
flag was set.Sampled
flag intrace_flags
onSpanContext
. This flag is propagated via theSpanContext
to child Spans. For more details see the W3C specification. This flag indicates that theSpan
has beensampled
and will be exported.SpanProcessor
s andSpanExporter
s will receive spans with theSampled
flag set for processing.
The flag combination SampledFlag == false
and is_recording
== truemeans that the current
Spandoes record information, but most likely the child
Span` will not.
The flag combination SampledFlag == true
and IsRecording == false
could cause gaps in the distributed trace, and because of this OpenTelemetry API
MUST NOT allow this combination.
Structs
SamplingResult | The result of sampling logic for a given |
Enums
SamplingDecision | Decision about whether or not to sample |
Traits
Sampler | The |