Merge pull request kubernetes#23274 from wojtek-t/speedup_scheduler_s…

…preading

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plugin/pkg/scheduler/algorithm/priorities/selector_spreading.go

@@ -17,10 +17,13 @@ limitations under the License.
 package priorities
 
 import (
+	"sync"
+
 	"github.com/golang/glog"
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/labels"
+	utilruntime "k8s.io/kubernetes/pkg/util/runtime"
 	"k8s.io/kubernetes/plugin/pkg/scheduler/algorithm"
 	schedulerapi "k8s.io/kubernetes/plugin/pkg/scheduler/api"
 	"k8s.io/kubernetes/plugin/pkg/scheduler/schedulercache"
@@ -79,8 +82,6 @@ func getZoneKey(node *api.Node) string {
 // pods which match the same service selectors or RC selectors as the pod being scheduled.
 // Where zone information is included on the nodes, it favors nodes in zones with fewer existing matching pods.
 func (s *SelectorSpread) CalculateSpreadPriority(pod *api.Pod, nodeNameToInfo map[string]*schedulercache.NodeInfo, nodeLister algorithm.NodeLister) (schedulerapi.HostPriorityList, error) {
-	var nsPods []*api.Pod
-
 	selectors := make([]labels.Selector, 0)
 	services, err := s.serviceLister.GetPodServices(pod)
 	if err == nil {
@@ -103,46 +104,70 @@ func (s *SelectorSpread) CalculateSpreadPriority(pod *api.Pod, nodeNameToInfo ma
 		}
 	}
 
-	if len(selectors) > 0 {
-		pods, err := s.podLister.List(labels.Everything())
-		if err != nil {
-			return nil, err
-		}
-		// consider only the pods that belong to the same namespace
-		for _, nsPod := range pods {
-			if nsPod.Namespace == pod.Namespace {
-				nsPods = append(nsPods, nsPod)
-			}
-		}
-	}
-
 	nodes, err := nodeLister.List()
 	if err != nil {
 		return nil, err
 	}
 
 	// Count similar pods by node
 	countsByNodeName := map[string]int{}
-	for _, pod := range nsPods {
-		// When we are replacing a failed pod, we often see the previous deleted version
-		// while scheduling the replacement.  Ignore the previous deleted version for spreading
-		// purposes (it can still be considered for resource restrictions etc.)
-		if pod.DeletionTimestamp != nil {
-			glog.V(2).Infof("skipping pending-deleted pod: %s/%s", pod.Namespace, pod.Name)
-			continue
-		}
-		matches := false
-		for _, selector := range selectors {
-			if selector.Matches(labels.Set(pod.ObjectMeta.Labels)) {
-				matches = true
-				break
-			}
+	countsByNodeNameLock := sync.Mutex{}
+
+	if len(selectors) > 0 {
+		// Create a number of go-routines that will be computing number
+		// of "similar" pods for given nodes.
+		workers := 16
+		toProcess := make(chan string, len(nodes.Items))
+		for i := range nodes.Items {
+			toProcess <- nodes.Items[i].Name
 		}
-		if !matches {
-			continue
+		close(toProcess)
+
+		wg := sync.WaitGroup{}
+		wg.Add(workers)
+		for i := 0; i < workers; i++ {
+			go func() {
+				defer utilruntime.HandleCrash()
+				defer wg.Done()
+				for {
+					nodeName, ok := <-toProcess
+					if !ok {
+						return
+					}
+					count := 0
+					for _, nodePod := range nodeNameToInfo[nodeName].Pods() {
+						if pod.Namespace != nodePod.Namespace {
+							continue
+						}
+						// When we are replacing a failed pod, we often see the previous
+						// deleted version while scheduling the replacement.
+						// Ignore the previous deleted version for spreading purposes
+						// (it can still be considered for resource restrictions etc.)
+						if nodePod.DeletionTimestamp != nil {
+							glog.V(4).Infof("skipping pending-deleted pod: %s/%s", nodePod.Namespace, nodePod.Name)
+							continue
+						}
+						matches := false
+						for _, selector := range selectors {
+							if selector.Matches(labels.Set(nodePod.ObjectMeta.Labels)) {
+								matches = true
+								break
+							}
+						}
+						if matches {
+							count++
+						}
+					}
+
+					func() {
+						countsByNodeNameLock.Lock()
+						defer countsByNodeNameLock.Unlock()
+						countsByNodeName[nodeName] = count
+					}()
+				}
+			}()
 		}
-
-		countsByNodeName[pod.Spec.NodeName]++
+		wg.Wait()
 	}
 
 	// Aggregate by-node information