[tailsamplingprocessor] Fix the decision timer metric to measure > 50ms

.chloggen/logiraptor_fix-decision-timer-metric.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: tailsamplingprocessor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix the decision timer metric to capture longer latencies beyond 50ms.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [37722]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: This changes the unit of the decision timer metric from microseconds to milliseconds.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

processor/tailsamplingprocessor/documentation.md

@@ -56,11 +56,11 @@ Latency (in microseconds) of a given sampling policy
 
 ### otelcol_processor_tail_sampling_sampling_decision_timer_latency
 
-Latency (in microseconds) of each run of the sampling decision timer
+Latency (in milliseconds) of each run of the sampling decision timer
 
 | Unit | Metric Type | Value Type |
 | ---- | ----------- | ---------- |
-| µs | Histogram | Int |
+| ms | Histogram | Int |
 
 ### otelcol_processor_tail_sampling_sampling_late_span_age
 

processor/tailsamplingprocessor/metadata.yaml

@@ -22,8 +22,8 @@ telemetry:
         bucket_boundaries: [1, 2, 5, 10, 25, 50, 75, 100, 150, 200, 300, 400, 500, 750, 1000, 2000, 3000, 4000, 5000, 10000, 20000, 30000, 50000]
 
     processor_tail_sampling_sampling_decision_timer_latency:
-      description: Latency (in microseconds) of each run of the sampling decision timer
-      unit: µs
+      description: Latency (in milliseconds) of each run of the sampling decision timer
+      unit: ms
       enabled: true
       histogram:
         value_type: int

processor/tailsamplingprocessor/processor.go

@@ -345,7 +345,7 @@ func (tsp *tailSamplingSpanProcessor) samplingPolicyOnTick() {
 
 		decision := tsp.makeDecision(id, trace, &metrics)
 
-		tsp.telemetry.ProcessorTailSamplingSamplingDecisionTimerLatency.Record(tsp.ctx, int64(time.Since(startTime)/time.Microsecond))
+		tsp.telemetry.ProcessorTailSamplingSamplingDecisionTimerLatency.Record(tsp.ctx, int64(time.Since(startTime)/time.Millisecond))
 		tsp.telemetry.ProcessorTailSamplingGlobalCountTracesSampled.Add(tsp.ctx, 1, decisionToAttribute[decision])
 
 		// Sampled or not, remove the batches

processor/tailsamplingprocessor/processor_telemetry_test.go

@@ -137,8 +137,8 @@ func TestMetricsAfterOneEvaluation(t *testing.T) {
 			opts: []metricdatatest.Option{metricdatatest.IgnoreTimestamp(), metricdatatest.IgnoreValue()},
 			m: metricdata.Metrics{
 				Name:        "otelcol_processor_tail_sampling_sampling_decision_timer_latency",
-				Description: "Latency (in microseconds) of each run of the sampling decision timer",
-				Unit:        "µs",
+				Description: "Latency (in milliseconds) of each run of the sampling decision timer",
+				Unit:        "ms",
 				Data: metricdata.Histogram[int64]{
 					Temporality: metricdata.CumulativeTemporality,
 					DataPoints:  []metricdata.HistogramDataPoint[int64]{{}},