kvserver: only start split tracing if we might record it

Previously we always started tracing in the split queue but only
recorded the span if expensive logging was enabled. Now we check earlier
in the process.

Part of: #104035

Release note: None

pkg/kv/kvserver/split_queue.go

@@ -242,33 +242,35 @@ func (sq *splitQueue) processAttemptWithTracing(
  ctx context.Context, r *Replica, confReader spanconfig.StoreReader,
 ) (processed bool, _ error) {
  processStart := r.Clock().PhysicalTime()
- ctx, sp := tracing.EnsureChildSpan(ctx, sq.Tracer, "split",
- tracing.WithRecording(tracingpb.RecordingVerbose))
+ startTracing := log.ExpensiveLogEnabled(ctx, 1)
+ var opts []tracing.SpanOption
+ if startTracing {
+ opts = append(opts, tracing.WithRecording(tracingpb.RecordingVerbose))
+ }
+ ctx, sp := tracing.EnsureChildSpan(ctx, sq.Tracer, "split", opts...)
  defer sp.Finish()
 
  processed, err := sq.processAttempt(ctx, r, confReader)
-
- // Utilize a new background context (properly annotated) to avoid writing
- // traces from a child context into its parent.
- {
- ctx := r.AnnotateCtx(sq.AnnotateCtx(context.Background()))
- processDuration := r.Clock().PhysicalTime().Sub(processStart)
- exceededDuration := sq.logTracesThreshold > time.Duration(0) && processDuration > sq.logTracesThreshold
-
- var traceOutput redact.RedactableString
- traceLoggingNeeded := (err != nil || exceededDuration) && log.ExpensiveLogEnabled(ctx, 1)
+ processDuration := r.Clock().PhysicalTime().Sub(processStart)
+ exceededDuration := sq.logTracesThreshold > time.Duration(0) && processDuration > sq.logTracesThreshold
+ var traceOutput redact.RedactableString
+ if startTracing {
+ // Utilize a new background context (properly annotated) to avoid writing
+ // traces from a child context into its parent.
+ ctx = r.AnnotateCtx(sq.AnnotateCtx(context.Background()))
+
+ traceLoggingNeeded := (err != nil || exceededDuration)
  if traceLoggingNeeded {
  // Add any trace filtering here if the output is too verbose.
  rec := sp.GetConfiguredRecording()
  traceOutput = redact.Sprintf("\ntrace:\n%s", rec)
  }
-
- if err != nil {
- log.Infof(ctx, "error during range split: %v%s", err, traceOutput)
- } else if exceededDuration {
- log.Infof(ctx, "range split took %s, exceeding threshold of %s%s",
- processDuration, sq.logTracesThreshold, traceOutput)
- }
+ }
+ if err != nil {
+ log.Infof(ctx, "error during range split: %v%s", err, traceOutput)
+ } else if exceededDuration {
+ log.Infof(ctx, "range split took %s, exceeding threshold of %s%s",
+ processDuration, sq.logTracesThreshold, traceOutput)
  }
 
  return processed, err