fixing some lint errors (#126)

Author: ahg-g

pkg/ext-proc/backend/provider.go

@@ -58,9 +58,8 @@ func (p *Provider) GetPodMetrics(pod Pod) (*PodMetrics, bool) {
 }
 
 func (p *Provider) Init(refreshPodsInterval, refreshMetricsInterval time.Duration) error {
-	if err := p.refreshPodsOnce(); err != nil {
-		klog.Errorf("Failed to init pods: %v", err)
-	}
+	p.refreshPodsOnce()
+
 	if err := p.refreshMetricsOnce(); err != nil {
 		klog.Errorf("Failed to init metrics: %v", err)
 	}
@@ -71,9 +70,7 @@ func (p *Provider) Init(refreshPodsInterval, refreshMetricsInterval time.Duratio
 	go func() {
 		for {
 			time.Sleep(refreshPodsInterval)
-			if err := p.refreshPodsOnce(); err != nil {
-				klog.V(4).Infof("Failed to refresh podslist pods: %v", err)
-			}
+			p.refreshPodsOnce()
 		}
 	}()
 
@@ -102,7 +99,7 @@ func (p *Provider) Init(refreshPodsInterval, refreshMetricsInterval time.Duratio
 
 // refreshPodsOnce lists pods and updates keys in the podMetrics map.
 // Note this function doesn't update the PodMetrics value, it's done separately.
-func (p *Provider) refreshPodsOnce() error {
+func (p *Provider) refreshPodsOnce() {
 	// merge new pods with cached ones.
 	// add new pod to the map
 	addNewPods := func(k, v any) bool {
@@ -128,7 +125,6 @@ func (p *Provider) refreshPodsOnce() error {
 	}
 	p.podMetrics.Range(mergeFn)
 	p.datastore.pods.Range(addNewPods)
-	return nil
 }
 
 func (p *Provider) refreshMetricsOnce() error {

pkg/ext-proc/backend/vllm/metrics.go

@@ -52,7 +52,9 @@ func (p *PodMetricsClientImpl) FetchMetrics(
 		klog.Errorf("failed to fetch metrics from %s: %v", pod, err)
 		return nil, fmt.Errorf("failed to fetch metrics from %s: %w", pod, err)
 	}
-	defer resp.Body.Close()
+	defer func() {
+		_ = resp.Body.Close()
+	}()
 
 	if resp.StatusCode != http.StatusOK {
 		klog.Errorf("unexpected status code from %s: %v", pod, resp.StatusCode)
@@ -76,17 +78,17 @@ func promToPodMetrics(
 ) (*backend.PodMetrics, error) {
 	var errs error
 	updated := existing.Clone()
-	runningQueueSize, _, err := getLatestMetric(metricFamilies, RunningQueueSizeMetricName)
+	runningQueueSize, err := getLatestMetric(metricFamilies, RunningQueueSizeMetricName)
 	errs = multierr.Append(errs, err)
 	if err == nil {
 		updated.RunningQueueSize = int(runningQueueSize.GetGauge().GetValue())
 	}
-	waitingQueueSize, _, err := getLatestMetric(metricFamilies, WaitingQueueSizeMetricName)
+	waitingQueueSize, err := getLatestMetric(metricFamilies, WaitingQueueSizeMetricName)
 	errs = multierr.Append(errs, err)
 	if err == nil {
 		updated.WaitingQueueSize = int(waitingQueueSize.GetGauge().GetValue())
 	}
-	cachePercent, _, err := getLatestMetric(metricFamilies, KVCacheUsagePercentMetricName)
+	cachePercent, err := getLatestMetric(metricFamilies, KVCacheUsagePercentMetricName)
 	errs = multierr.Append(errs, err)
 	if err == nil {
 		updated.KVCacheUsagePercent = cachePercent.GetGauge().GetValue()
@@ -151,14 +153,14 @@ func getLatestLoraMetric(metricFamilies map[string]*dto.MetricFamily) (*dto.Metr
 
 // getLatestMetric gets the latest metric of a family. This should be used to get the latest Gauge metric.
 // Since vllm doesn't set the timestamp in metric, this metric essentially gets the first metric.
-func getLatestMetric(metricFamilies map[string]*dto.MetricFamily, metricName string) (*dto.Metric, time.Time, error) {
+func getLatestMetric(metricFamilies map[string]*dto.MetricFamily, metricName string) (*dto.Metric, error) {
 	mf, ok := metricFamilies[metricName]
 	if !ok {
 		klog.Warningf("metric family %q not found", metricName)
-		return nil, time.Time{}, fmt.Errorf("metric family %q not found", metricName)
+		return nil, fmt.Errorf("metric family %q not found", metricName)
 	}
 	if len(mf.GetMetric()) == 0 {
-		return nil, time.Time{}, fmt.Errorf("no metrics available for %q", metricName)
+		return nil, fmt.Errorf("no metrics available for %q", metricName)
 	}
 	var latestTs int64
 	var latest *dto.Metric
@@ -169,5 +171,5 @@ func getLatestMetric(metricFamilies map[string]*dto.MetricFamily, metricName str
 		}
 	}
 	klog.V(4).Infof("Got metric value %+v for metric %v", latest, metricName)
-	return latest, time.Unix(0, latestTs*1000), nil
+	return latest, nil
 }

pkg/ext-proc/scheduling/filter.go

@@ -157,9 +157,10 @@ func leastKVCacheFilterFunc(req *LLMRequest, pods []*backend.PodMetrics) ([]*bac
 type podPredicate func(req *LLMRequest, pod *backend.PodMetrics) bool
 
 // We consider serving an adapter low cost it the adapter is active in the model server, or the
-// model server has room to load the adapter. The lowLoRACostPredicate ensures weak affinity by spreading the
-// load of a LoRA adapter across multiple pods, avoiding "pinning" all requests to a single pod.
-// This gave good performance in our initial benchmarking results in the scenario where # of lora slots > # of lora adapters.
+// model server has room to load the adapter. The lowLoRACostPredicate ensures weak affinity by
+// spreading the load of a LoRA adapter across multiple pods, avoiding "pinning" all requests to
+// a single pod. This gave good performance in our initial benchmarking results in the scenario
+// where # of lora slots > # of lora adapters.
 func lowLoRACostPredicate(req *LLMRequest, pod *backend.PodMetrics) bool {
 	_, ok := pod.ActiveModels[req.ResolvedTargetModel]
 	return ok || len(pod.ActiveModels) < pod.MaxActiveModels

pkg/ext-proc/scheduling/scheduler.go

@@ -84,7 +84,8 @@ var (
 			name: "drop request",
 			filter: func(req *LLMRequest, pods []*backend.PodMetrics) ([]*backend.PodMetrics, error) {
 				klog.Infof("Dropping request %v", req)
-				return []*backend.PodMetrics{}, status.Errorf(codes.ResourceExhausted, "dropping request due to limited backend resources")
+				return []*backend.PodMetrics{}, status.Errorf(
+					codes.ResourceExhausted, "dropping request due to limited backend resources")
 			},
 		},
 	}
@@ -114,7 +115,8 @@ func (s *Scheduler) Schedule(req *LLMRequest) (targetPod backend.Pod, err error)
 	klog.V(3).Infof("request: %v; metrics: %+v", req, s.podMetricsProvider.AllPodMetrics())
 	pods, err := s.filter.Filter(req, s.podMetricsProvider.AllPodMetrics())
 	if err != nil || len(pods) == 0 {
-		return backend.Pod{}, fmt.Errorf("failed to apply filter, resulted %v pods, this should never happen: %w", len(pods), err)
+		return backend.Pod{}, fmt.Errorf(
+			"failed to apply filter, resulted %v pods, this should never happen: %w", len(pods), err)
 	}
 	klog.V(3).Infof("Going to randomly select a pod from the candidates: %+v", pods)
 	i := rand.Intn(len(pods))