Compute priorities in parallel

plugin/pkg/scheduler/generic_scheduler.go

@@ -238,8 +238,6 @@ func PrioritizeNodes(
 	nodes []*api.Node,
 	extenders []algorithm.SchedulerExtender,
 ) (schedulerapi.HostPriorityList, error) {
-	result := make(schedulerapi.HostPriorityList, 0, len(nodes))
-
 	// If no priority configs are provided, then the EqualPriority function is applied
 	// This is required to generate the priority list in the required format
 	if len(priorityConfigs) == 0 && len(extenders) == 0 {
@@ -249,61 +247,80 @@ func PrioritizeNodes(
 	var (
 		mu   = sync.Mutex{}
 		wg   = sync.WaitGroup{}
-		combinedScores = make(map[string]int, len(nodeNameToInfo))
 		errs []error
 	)
+	appendError := func(err error) {
+		mu.Lock()
+		defer mu.Unlock()
+		errs = append(errs, err)
+	}
 
 	meta := priorities.PriorityMetadata(pod, nodes)
-	for _, priorityConfig := range priorityConfigs {
-		// skip the priority function if the weight is specified as 0
-		if priorityConfig.Weight == 0 {
-			continue
+	results := make([]schedulerapi.HostPriorityList, 0, len(priorityConfigs))
+	for range priorityConfigs {
+		results = append(results, nil)
 	}
-
+	for i, priorityConfig := range priorityConfigs {
+		if priorityConfig.Function != nil {
+			// DEPRECATED
 			wg.Add(1)
-		go func(config algorithm.PriorityConfig) {
+			go func(index int, config algorithm.PriorityConfig) {
 				defer wg.Done()
-			weight := config.Weight
-
-			prioritizedList, err := func() (schedulerapi.HostPriorityList, error) {
-				if config.Function != nil {
-					return config.Function(pod, nodeNameToInfo, nodes)
-				}
-				prioritizedList := make(schedulerapi.HostPriorityList, 0, len(nodes))
-				for i := range nodes {
-					hostResult, err := config.Map(pod, meta, nodeNameToInfo[nodes[i].Name])
+				var err error
+				results[index], err = config.Function(pod, nodeNameToInfo, nodes)
 				if err != nil {
-						return nil, err
+					appendError(err)
 				}
-					prioritizedList = append(prioritizedList, hostResult)
+			}(i, priorityConfig)
+		} else {
+			results[i] = make(schedulerapi.HostPriorityList, len(nodes))
 		}
-				if config.Reduce != nil {
-					if err := config.Reduce(prioritizedList); err != nil {
-						return nil, err
 	}
+	processNode := func(index int) {
+		nodeInfo := nodeNameToInfo[nodes[index].Name]
+		var err error
+		for i := range priorityConfigs {
+			if priorityConfigs[i].Function != nil {
+				continue
 			}
-				return prioritizedList, nil
-			}()
-
-			mu.Lock()
-			defer mu.Unlock()
+			results[i][index], err = priorityConfigs[i].Map(pod, meta, nodeInfo)
 			if err != nil {
-				errs = append(errs, err)
+				appendError(err)
 				return
 			}
-			for i := range prioritizedList {
-				host, score := prioritizedList[i].Host, prioritizedList[i].Score
-				combinedScores[host] += score * weight
 		}
-		}(priorityConfig)
 	}
-	// wait for all go routines to finish
+	workqueue.Parallelize(16, len(nodes), processNode)
+	for i, priorityConfig := range priorityConfigs {
+		if priorityConfig.Reduce == nil {
+			continue
+		}
+		wg.Add(1)
+		go func(index int, config algorithm.PriorityConfig) {
+			defer wg.Done()
+			if err := config.Reduce(results[index]); err != nil {
+				appendError(err)
+			}
+		}(i, priorityConfig)
+	}
+	// Wait for all computations to be finished.
 	wg.Wait()
 	if len(errs) != 0 {
 		return schedulerapi.HostPriorityList{}, errors.NewAggregate(errs)
 	}
 
+	// Summarize all scores.
+	result := make(schedulerapi.HostPriorityList, 0, len(nodes))
+	// TODO: Consider parallelizing it.
+	for i := range nodes {
+		result = append(result, schedulerapi.HostPriority{Host: nodes[i].Name, Score: 0})
+		for j := range priorityConfigs {
+			result[i].Score += results[j][i].Score * priorityConfigs[j].Weight
+		}
+	}
+
 	if len(extenders) != 0 && nodes != nil {
+		combinedScores := make(map[string]int, len(nodeNameToInfo))
 		for _, extender := range extenders {
 			wg.Add(1)
 			go func(ext algorithm.SchedulerExtender) {
@@ -321,13 +338,17 @@ func PrioritizeNodes(
 				mu.Unlock()
 			}(extender)
 		}
-	}
 		// wait for all go routines to finish
 		wg.Wait()
+		for i := range result {
+			result[i].Score += combinedScores[result[i].Host]
+		}
+	}
 
-	for host, score := range combinedScores {
-		glog.V(10).Infof("Host %s Score %d", host, score)
-		result = append(result, schedulerapi.HostPriority{Host: host, Score: score})
+	if glog.V(10) {
+		for i := range result {
+			glog.V(10).Infof("Host %s => Score %d", result[i].Host, result[i].Score)
+		}
 	}
 	return result, nil
 }