Adaptive Tail Sampling Processor

OpenTelemetry Collector processor · contrib distribution

The Adaptive Tail Sampling Processor performs adaptive trace sampling using first-match rules-based routing to adaptive samplers. Each sampler produces a known sample rate which is encoded as ot=th in W3C TraceState for correct downstream metric weighting.

Component ID: contrib-adaptivetailsamplingprocessor
Name: adaptivetailsamplingprocessor
Type: processor
Distribution: contrib
Repository: opentelemetry-collector-contrib

Stability

Level	Signals
development	traces

Internal telemetry

Metric	Type	Value type	Unit	Stability	Enabled	Description
`processor_adaptive_tail_sampling_decision_sample_rate`	histogram	int	{rate}	development	yes	Distribution of effective sample rates produced per rule. Useful for detecting adaptive samplers settling at unexpected rates.
`processor_adaptive_tail_sampling_decision_triggers`	sum (monotonic)	int	{decisions}	development	yes	Number of trace decisions made, labelled by which event triggered the decision (root_span, trace_timeout, eviction, shutdown, span_limit).
`processor_adaptive_tail_sampling_fingerprint_duration`	histogram	int	us	development	yes	Time spent extracting a rule's fingerprint per decision, in microseconds, labelled by rule. A relative signal for spotting expensive fingerprints (wide scopes such as any. on large traces); absolute values depend on host and load.
`processor_adaptive_tail_sampling_incoming_tracestate_unparseable`	sum (monotonic)	int	{spans}	development	yes	Number of spans whose incoming W3C tracestate could not be parsed when applying the sampling threshold.
`processor_adaptive_tail_sampling_ottl_eval_errors`	sum (monotonic)	int	{errors}	development	yes	Number of OTTL condition evaluation errors, labelled by the rule the condition belongs to (_root_span_condition for the root-span condition).
`processor_adaptive_tail_sampling_trace_span_count`	histogram	int	{spans}	development	yes	Distribution of buffered span counts per trace at decision time, labelled by rule. Useful for sizing span_limit against the real trace-size distribution.
`processor_adaptive_tail_sampling_traces_active`	gauge	int	{traces}	development	yes	Number of traces currently in the accumulation buffer awaiting a decision.
`processor_adaptive_tail_sampling_traces_dropped`	sum (monotonic)	int	{traces}	development	yes	Number of traces that were dropped, labelled by the rule that selected them. Sentinel rule values are prefixed with an underscore (e.g. _unmatched, _eviction).
`processor_adaptive_tail_sampling_traces_evicted`	sum (monotonic)	int	{traces}	development	yes	Number of traces evicted from the buffer due to num_traces pressure. Evicted traces are decided immediately per the configured eviction policy.
`processor_adaptive_tail_sampling_traces_sampled`	sum (monotonic)	int	{traces}	development	yes	Number of traces that were sampled, labelled by the rule that selected them. Sentinel rule values are prefixed with an underscore (e.g. _eviction).