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handlers: guard latency metrics when timestamps are absent #1963

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Copilot Jul 10, 2026
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handlers: guard latency metrics when timestamps are absent
Copilot Jul 10, 2026
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14 changes: 10 additions & 4 deletions pkg/epp/handlers/response.go
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Original file line number Diff line number Diff line change
Expand Up @@ -86,11 +86,17 @@ func (s *StreamingServer) HandleResponseBody(ctx context.Context, reqCtx *Reques
}
}
if endOfStream {
metrics.RecordNormalizedTimePerOutputToken(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.RequestReceivedTimestamp, reqCtx.ResponseCompleteTimestamp, reqCtx.Usage.CompletionTokens)
metrics.RecordRequestLatencies(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.RequestReceivedTimestamp, reqCtx.ResponseCompleteTimestamp)
if !reqCtx.RequestReceivedTimestamp.IsZero() && !reqCtx.ResponseCompleteTimestamp.IsZero() {
metrics.RecordNormalizedTimePerOutputToken(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.RequestReceivedTimestamp, reqCtx.ResponseCompleteTimestamp, reqCtx.Usage.CompletionTokens)
metrics.RecordRequestLatencies(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.RequestReceivedTimestamp, reqCtx.ResponseCompleteTimestamp)
}
metrics.RecordResponseSizes(reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.ResponseSize)
metrics.RecordRequestTTFT(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.modelServerStreaming, reqCtx.RequestReceivedTimestamp, reqCtx.FirstTokenTimestamp)
metrics.RecordRequestTPOT(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.RequestReceivedTimestamp, reqCtx.FirstTokenTimestamp, reqCtx.ResponseCompleteTimestamp, reqCtx.Usage.CompletionTokens)
if !reqCtx.RequestReceivedTimestamp.IsZero() && !reqCtx.FirstTokenTimestamp.IsZero() {
metrics.RecordRequestTTFT(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.modelServerStreaming, reqCtx.RequestReceivedTimestamp, reqCtx.FirstTokenTimestamp)
}
if !reqCtx.RequestReceivedTimestamp.IsZero() && !reqCtx.FirstTokenTimestamp.IsZero() && !reqCtx.ResponseCompleteTimestamp.IsZero() {
metrics.RecordRequestTPOT(ctx, reqCtx.IncomingModelName, reqCtx.TargetModelName, fairnessID, priority, reqCtx.RequestReceivedTimestamp, reqCtx.FirstTokenTimestamp, reqCtx.ResponseCompleteTimestamp, reqCtx.Usage.CompletionTokens)
}
}
return s.director.HandleResponseBody(ctx, reqCtx, endOfStream)
}
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57 changes: 57 additions & 0 deletions pkg/epp/handlers/response_test.go
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Expand Up @@ -309,6 +309,63 @@ func TestHandleResponseBodyWithoutSchedulingRequest(t *testing.T) {
require.Equal(t, uint64(1), histogram.GetSampleCount())
}

// TestHandleResponseBodyZeroTimestamps verifies that end-of-stream handling with zero
// timestamps does not emit latency metrics or produce error log entries.
func TestHandleResponseBodyZeroTimestamps(t *testing.T) {
ctx := logutil.NewTestLoggerIntoContext(context.Background())
eppmetrics.Register()
eppmetrics.Reset()
t.Cleanup(eppmetrics.Reset)

server := &StreamingServer{
parserRegistry: NewParserRegistry([]fwkrh.Parser{openai.NewOpenAIParser()}, logr.Discard()),
}
server.director = &mockDirector{}
// RequestReceivedTimestamp, FirstTokenTimestamp, and ResponseCompleteTimestamp are all zero.
reqCtx := &RequestContext{
IncomingModelName: "incoming-model",
TargetModelName: "target-model",
Response: &Response{
Headers: map[string]string{},
},
SchedulingRequest: &fwksched.InferenceRequest{FairnessID: metadata.DefaultFairnessID},
}

require.NotPanics(t, func() {
server.HandleResponseBody(ctx, reqCtx, []byte("data"), true)
})

// Latency metrics must not be recorded when timestamps are absent.
families, err := ctrlmetrics.Registry.Gather()
require.NoError(t, err)
latencyMetrics := []string{
"llm_d_epp_request_ntpot_seconds",
"llm_d_epp_request_duration_seconds",
"llm_d_epp_request_ttft_seconds",
"llm_d_epp_request_streaming_tpot_seconds",
}
for _, family := range families {
for _, name := range latencyMetrics {
if family.GetName() == name {
for _, metric := range family.GetMetric() {
if metricHasLabels(metric, map[string]string{"model_name": "incoming-model"}) {
t.Errorf("latency metric %q must not be recorded with zero timestamps, got sample count %d",
name, metric.GetHistogram().GetSampleCount())
}
}
}
}
}

// ResponseSize should still be recorded.
sizeHistogram := findHistogramMetric(t, "llm_d_epp_response_size_bytes", map[string]string{
"model_name": "incoming-model",
"target_model_name": "target-model",
"fairness_id": metadata.DefaultFairnessID,
})
require.Equal(t, uint64(1), sizeHistogram.GetSampleCount())
}

func findHistogramMetric(t *testing.T, name string, labels map[string]string) *dto.Histogram {
t.Helper()

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