Merge pull request #97184 from chendave/add_status

Show the details on the failure of preemption

pkg/scheduler/core/generic_scheduler.go

@@ -20,8 +20,6 @@ import (
 	"context"
 	"fmt"
 	"math/rand"
-	"sort"
-	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -52,42 +50,9 @@ const (
 	minFeasibleNodesPercentageToFind = 5
 )
 
-// FitError describes a fit error of a pod.
-type FitError struct {
-	Pod                   *v1.Pod
-	NumAllNodes           int
-	FilteredNodesStatuses framework.NodeToStatusMap
-}
-
 // ErrNoNodesAvailable is used to describe the error that no nodes available to schedule pods.
 var ErrNoNodesAvailable = fmt.Errorf("no nodes available to schedule pods")
 
-const (
-	// NoNodeAvailableMsg is used to format message when no nodes available.
-	NoNodeAvailableMsg = "0/%v nodes are available"
-)
-
-// Error returns detailed information of why the pod failed to fit on each node
-func (f *FitError) Error() string {
-	reasons := make(map[string]int)
-	for _, status := range f.FilteredNodesStatuses {
-		for _, reason := range status.Reasons() {
-			reasons[reason]++
-		}
-	}
-
-	sortReasonsHistogram := func() []string {
-		var reasonStrings []string
-		for k, v := range reasons {
-			reasonStrings = append(reasonStrings, fmt.Sprintf("%v %v", v, k))
-		}
-		sort.Strings(reasonStrings)
-		return reasonStrings
-	}
-	reasonMsg := fmt.Sprintf(NoNodeAvailableMsg+": %v.", f.NumAllNodes, strings.Join(sortReasonsHistogram(), ", "))
-	return reasonMsg
-}
-
 // ScheduleAlgorithm is an interface implemented by things that know how to schedule pods
 // onto machines.
 // TODO: Rename this type.
@@ -147,7 +112,7 @@ func (g *genericScheduler) Schedule(ctx context.Context, fwk framework.Framework
 	trace.Step("Computing predicates done")
 
 	if len(feasibleNodes) == 0 {
-		return result, &FitError{
+		return result, &framework.FitError{
 			Pod:                   pod,
 			NumAllNodes:           g.nodeInfoSnapshot.NumNodes(),
 			FilteredNodesStatuses: filteredNodesStatuses,

pkg/scheduler/core/generic_scheduler_test.go

@@ -289,7 +289,7 @@ func TestGenericScheduler(t *testing.T) {
 			nodes: []string{"machine1", "machine2"},
 			pod:   &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "2", UID: types.UID("2")}},
 			name:  "test 1",
-			wErr: &FitError{
+			wErr: &framework.FitError{
 				Pod:         &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "2", UID: types.UID("2")}},
 				NumAllNodes: 2,
 				FilteredNodesStatuses: framework.NodeToStatusMap{
@@ -374,7 +374,7 @@ func TestGenericScheduler(t *testing.T) {
 			nodes: []string{"3", "2", "1"},
 			pod:   &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "2", UID: types.UID("2")}},
 			name:  "test 7",
-			wErr: &FitError{
+			wErr: &framework.FitError{
 				Pod:         &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "2", UID: types.UID("2")}},
 				NumAllNodes: 3,
 				FilteredNodesStatuses: framework.NodeToStatusMap{
@@ -406,7 +406,7 @@ func TestGenericScheduler(t *testing.T) {
 			pod:   &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "2", UID: types.UID("2")}},
 			nodes: []string{"1", "2"},
 			name:  "test 8",
-			wErr: &FitError{
+			wErr: &framework.FitError{
 				Pod:         &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "2", UID: types.UID("2")}},
 				NumAllNodes: 2,
 				FilteredNodesStatuses: framework.NodeToStatusMap{
@@ -640,7 +640,7 @@ func TestGenericScheduler(t *testing.T) {
 			nodes:         []string{"3"},
 			pod:           &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "test-filter", UID: types.UID("test-filter")}},
 			expectedHosts: nil,
-			wErr: &FitError{
+			wErr: &framework.FitError{
 				Pod:         &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "test-filter", UID: types.UID("test-filter")}},
 				NumAllNodes: 1,
 				FilteredNodesStatuses: framework.NodeToStatusMap{
@@ -662,7 +662,7 @@ func TestGenericScheduler(t *testing.T) {
 			nodes:         []string{"3"},
 			pod:           &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "test-filter", UID: types.UID("test-filter")}},
 			expectedHosts: nil,
-			wErr: &FitError{
+			wErr: &framework.FitError{
 				Pod:         &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "test-filter", UID: types.UID("test-filter")}},
 				NumAllNodes: 1,
 				FilteredNodesStatuses: framework.NodeToStatusMap{
@@ -699,7 +699,7 @@ func TestGenericScheduler(t *testing.T) {
 			nodes:         []string{"1", "2"},
 			pod:           &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "test-prefilter", UID: types.UID("test-prefilter")}},
 			expectedHosts: nil,
-			wErr: &FitError{
+			wErr: &framework.FitError{
 				Pod:         &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "test-prefilter", UID: types.UID("test-prefilter")}},
 				NumAllNodes: 2,
 				FilteredNodesStatuses: framework.NodeToStatusMap{

pkg/scheduler/factory.go

@@ -318,7 +318,7 @@ func MakeDefaultErrorFunc(client clientset.Interface, podLister corelisters.PodL
 		pod := podInfo.Pod
 		if err == core.ErrNoNodesAvailable {
 			klog.V(2).InfoS("Unable to schedule pod; no nodes are registered to the cluster; waiting", "pod", klog.KObj(pod))
-		} else if _, ok := err.(*core.FitError); ok {
+		} else if _, ok := err.(*framework.FitError); ok {
 			klog.V(2).InfoS("Unable to schedule pod; no fit; waiting", "pod", klog.KObj(pod), "err", err)
 		} else if apierrors.IsNotFound(err) {
 			klog.V(2).InfoS("Unable to schedule pod, possibly due to node not found; waiting", "pod", klog.KObj(pod), "err", err)

pkg/scheduler/framework/interface.go

@@ -63,7 +63,7 @@ const (
 	// scheduler skip preemption.
 	// The accompanying status message should explain why the pod is unschedulable.
 	Unschedulable
-	// UnschedulableAndUnresolvable is used when a PreFilter plugin finds a pod unschedulable and
+	// UnschedulableAndUnresolvable is used when a plugin finds a pod unschedulable and
 	// preemption would not change anything. Plugins should return Unschedulable if it is possible
 	// that the pod can get scheduled with preemption.
 	// The accompanying status message should explain why the pod is unschedulable.

pkg/scheduler/framework/plugins/defaultpreemption/default_preemption.go

@@ -22,6 +22,7 @@ import (
 	"math"
 	"math/rand"
 	"sort"
+	"sync"
 	"sync/atomic"
 
 	"k8s.io/klog/v2"
@@ -93,8 +94,12 @@ func (pl *DefaultPreemption) PostFilter(ctx context.Context, state *framework.Cy
 
 	nnn, err := pl.preempt(ctx, state, pod, m)
 	if err != nil {
+		if _, ok := err.(*framework.FitError); ok {
+			return nil, framework.NewStatus(framework.Unschedulable, err.Error())
+		}
 		return nil, framework.AsStatus(err)
 	}
+	// This happens when the pod is not eligible for preemption or extenders filtered all candidates.
 	if nnn == "" {
 		return nil, framework.NewStatus(framework.Unschedulable)
 	}
@@ -214,8 +219,16 @@ func (pl *DefaultPreemption) FindCandidates(ctx context.Context, state *framewor
 		}
 		klog.Infof("from a pool of %d nodes (offset: %d, sample %d nodes: %v), ~%d candidates will be chosen", len(potentialNodes), offset, len(sample), sample, numCandidates)
 	}
-
-	return dryRunPreemption(ctx, pl.fh, state, pod, potentialNodes, pdbs, offset, numCandidates), nil
+	candidates, nodeStatuses := dryRunPreemption(ctx, pl.fh, state, pod, potentialNodes, pdbs, offset, numCandidates)
+	// Return a FitError only when there are no candidates that fit the pod.
+	if len(candidates) == 0 {
+		return candidates, &framework.FitError{
+			Pod:                   pod,
+			NumAllNodes:           len(potentialNodes),
+			FilteredNodesStatuses: nodeStatuses,
+		}
+	}
+	return candidates, nil
 }
 
 // PodEligibleToPreemptOthers determines whether this pod should be considered
@@ -301,21 +314,22 @@ func (cl *candidateList) get() []Candidate {
 }
 
 // dryRunPreemption simulates Preemption logic on <potentialNodes> in parallel,
-// and returns preemption candidates. The number of candidates depends on the
-// constraints defined in the plugin's args. In the returned list of
+// returns preemption candidates and a map indicating filtered nodes statuses.
+// The number of candidates depends on the constraints defined in the plugin's args. In the returned list of
 // candidates, ones that do not violate PDB are preferred over ones that do.
 func dryRunPreemption(ctx context.Context, fh framework.Handle,
 	state *framework.CycleState, pod *v1.Pod, potentialNodes []*framework.NodeInfo,
-	pdbs []*policy.PodDisruptionBudget, offset int32, numCandidates int32) []Candidate {
+	pdbs []*policy.PodDisruptionBudget, offset int32, numCandidates int32) ([]Candidate, framework.NodeToStatusMap) {
 	nonViolatingCandidates := newCandidateList(numCandidates)
 	violatingCandidates := newCandidateList(numCandidates)
 	parallelCtx, cancel := context.WithCancel(ctx)
-
+	nodeStatuses := make(framework.NodeToStatusMap)
+	var statusesLock sync.Mutex
 	checkNode := func(i int) {
 		nodeInfoCopy := potentialNodes[(int(offset)+i)%len(potentialNodes)].Clone()
 		stateCopy := state.Clone()
-		pods, numPDBViolations, fits := selectVictimsOnNode(ctx, fh, stateCopy, pod, nodeInfoCopy, pdbs)
-		if fits {
+		pods, numPDBViolations, status := selectVictimsOnNode(ctx, fh, stateCopy, pod, nodeInfoCopy, pdbs)
+		if status.IsSuccess() {
 			victims := extenderv1.Victims{
 				Pods:             pods,
 				NumPDBViolations: int64(numPDBViolations),
@@ -333,10 +347,14 @@ func dryRunPreemption(ctx context.Context, fh framework.Handle,
 			if nvcSize > 0 && nvcSize+vcSize >= numCandidates {
 				cancel()
 			}
+		} else {
+			statusesLock.Lock()
+			nodeStatuses[nodeInfoCopy.Node().Name] = status
+			statusesLock.Unlock()
 		}
 	}
 	parallelize.Until(parallelCtx, len(potentialNodes), checkNode)
-	return append(nonViolatingCandidates.get(), violatingCandidates.get()...)
+	return append(nonViolatingCandidates.get(), violatingCandidates.get()...), nodeStatuses
 }
 
 // CallExtenders calls given <extenders> to select the list of feasible candidates.
@@ -578,9 +596,8 @@ func selectVictimsOnNode(
 	pod *v1.Pod,
 	nodeInfo *framework.NodeInfo,
 	pdbs []*policy.PodDisruptionBudget,
-) ([]*v1.Pod, int, bool) {
+) ([]*v1.Pod, int, *framework.Status) {
 	var potentialVictims []*v1.Pod
-
 	ph := fh.PreemptHandle()
 	removePod := func(rp *v1.Pod) error {
 		if err := nodeInfo.RemovePod(rp); err != nil {
@@ -607,14 +624,15 @@ func selectVictimsOnNode(
 		if corev1helpers.PodPriority(p.Pod) < podPriority {
 			potentialVictims = append(potentialVictims, p.Pod)
 			if err := removePod(p.Pod); err != nil {
-				return nil, 0, false
+				return nil, 0, framework.NewStatus(framework.Error, err.Error())
 			}
 		}
 	}
 
 	// No potential victims are found, and so we don't need to evaluate the node again since its state didn't change.
 	if len(potentialVictims) == 0 {
-		return nil, 0, false
+		message := fmt.Sprintf("No victims found on node %v for preemptor pod %v", nodeInfo.Node().Name, pod.Name)
+		return nil, 0, framework.NewStatus(framework.UnschedulableAndUnresolvable, message)
 	}
 
 	// If the new pod does not fit after removing all the lower priority pods,
@@ -624,11 +642,7 @@ func selectVictimsOnNode(
 	// support this case for performance reasons. Having affinity to lower
 	// priority pods is not a recommended configuration anyway.
 	if status := fh.RunFilterPluginsWithNominatedPods(ctx, state, pod, nodeInfo); !status.IsSuccess() {
-		if status.Code() == framework.Error {
-			klog.Warningf("Encountered error while selecting victims on node %v: %v", nodeInfo.Node().Name, status.AsError())
-		}
-
-		return nil, 0, false
+		return nil, 0, status
 	}
 	var victims []*v1.Pod
 	numViolatingVictim := 0
@@ -654,8 +668,7 @@ func selectVictimsOnNode(
 	}
 	for _, p := range violatingVictims {
 		if fits, err := reprievePod(p); err != nil {
-			klog.Warningf("Failed to reprieve pod %q: %v", p.Name, err)
-			return nil, 0, false
+			return nil, 0, framework.NewStatus(framework.Error, err.Error())
 		} else if !fits {
 			numViolatingVictim++
 		}
@@ -663,11 +676,10 @@ func selectVictimsOnNode(
 	// Now we try to reprieve non-violating victims.
 	for _, p := range nonViolatingVictims {
 		if _, err := reprievePod(p); err != nil {
-			klog.Warningf("Failed to reprieve pod %q: %v", p.Name, err)
-			return nil, 0, false
+			return nil, 0, framework.NewStatus(framework.Error, err.Error())
 		}
 	}
-	return victims, numViolatingVictim, true
+	return victims, numViolatingVictim, framework.NewStatus(framework.Success)
 }
 
 // PrepareCandidate does some preparation work before nominating the selected candidate:

pkg/scheduler/framework/plugins/defaultpreemption/default_preemption_test.go

@@ -100,6 +100,7 @@ func getDefaultDefaultPreemptionArgs() *config.DefaultPreemptionArgs {
 
 func TestPostFilter(t *testing.T) {
 	onePodRes := map[v1.ResourceName]string{v1.ResourcePods: "1"}
+	nodeRes := map[v1.ResourceName]string{v1.ResourceCPU: "200m", v1.ResourceMemory: "400"}
 	tests := []struct {
 		name                  string
 		pod                   *v1.Pod
@@ -138,7 +139,7 @@ func TestPostFilter(t *testing.T) {
 				"node1": framework.NewStatus(framework.Unschedulable),
 			},
 			wantResult: nil,
-			wantStatus: framework.NewStatus(framework.Unschedulable),
+			wantStatus: framework.NewStatus(framework.Unschedulable, "0/1 nodes are available: 1 No victims found on node node1 for preemptor pod p."),
 		},
 		{
 			name: "preemption should respect filteredNodesStatuses",
@@ -194,6 +195,42 @@ func TestPostFilter(t *testing.T) {
 			},
 			wantStatus: framework.NewStatus(framework.Success),
 		},
+		{
+			name: "no candidate nodes found, no enough resource after removing low priority pods",
+			pod:  st.MakePod().Name("p").UID("p").Namespace(v1.NamespaceDefault).Priority(highPriority).Req(largeRes).Obj(),
+			pods: []*v1.Pod{
+				st.MakePod().Name("p1").UID("p1").Namespace(v1.NamespaceDefault).Node("node1").Obj(),
+				st.MakePod().Name("p2").UID("p2").Namespace(v1.NamespaceDefault).Node("node2").Obj(),
+			},
+			nodes: []*v1.Node{
+				st.MakeNode().Name("node1").Capacity(nodeRes).Obj(), // no enough CPU resource
+				st.MakeNode().Name("node2").Capacity(nodeRes).Obj(), // no enough CPU resource
+			},
+			filteredNodesStatuses: framework.NodeToStatusMap{
+				"node1": framework.NewStatus(framework.Unschedulable),
+				"node2": framework.NewStatus(framework.Unschedulable),
+			},
+			wantResult: nil,
+			wantStatus: framework.NewStatus(framework.Unschedulable, "0/2 nodes are available: 2 Insufficient cpu."),
+		},
+		{
+			name: "no candidate nodes found with mixed reasons, no lower priority pod and no enough CPU resource",
+			pod:  st.MakePod().Name("p").UID("p").Namespace(v1.NamespaceDefault).Priority(highPriority).Req(largeRes).Obj(),
+			pods: []*v1.Pod{
+				st.MakePod().Name("p1").UID("p1").Namespace(v1.NamespaceDefault).Node("node1").Priority(highPriority).Obj(),
+				st.MakePod().Name("p2").UID("p2").Namespace(v1.NamespaceDefault).Node("node2").Obj(),
+			},
+			nodes: []*v1.Node{
+				st.MakeNode().Name("node1").Capacity(onePodRes).Obj(), // no pod will be preempted
+				st.MakeNode().Name("node2").Capacity(nodeRes).Obj(),   // no enough CPU resource
+			},
+			filteredNodesStatuses: framework.NodeToStatusMap{
+				"node1": framework.NewStatus(framework.Unschedulable),
+				"node2": framework.NewStatus(framework.Unschedulable),
+			},
+			wantResult: nil,
+			wantStatus: framework.NewStatus(framework.Unschedulable, "0/2 nodes are available: 1 Insufficient cpu, 1 No victims found on node node1 for preemptor pod p."),
+		},
 	}
 
 	for _, tt := range tests {
@@ -978,7 +1015,7 @@ func TestDryRunPreemption(t *testing.T) {
 					t.Errorf("cycle %d: Unexpected PreFilter Status: %v", cycle, status)
 				}
 				offset, numCandidates := pl.getOffsetAndNumCandidates(int32(len(nodeInfos)))
-				got := dryRunPreemption(context.Background(), fwk, state, pod, nodeInfos, tt.pdbs, offset, numCandidates)
+				got, _ := dryRunPreemption(context.Background(), fwk, state, pod, nodeInfos, tt.pdbs, offset, numCandidates)
 				if err != nil {
 					t.Fatal(err)
 				}
@@ -1201,7 +1238,7 @@ func TestSelectBestCandidate(t *testing.T) {
 
 			pl := &DefaultPreemption{args: *getDefaultDefaultPreemptionArgs()}
 			offset, numCandidates := pl.getOffsetAndNumCandidates(int32(len(nodeInfos)))
-			candidates := dryRunPreemption(context.Background(), fwk, state, tt.pod, nodeInfos, nil, offset, numCandidates)
+			candidates, _ := dryRunPreemption(context.Background(), fwk, state, tt.pod, nodeInfos, nil, offset, numCandidates)
 			s := SelectCandidate(candidates)
 			found := false
 			for _, nodeName := range tt.expected {

pkg/scheduler/framework/types.go

@@ -19,6 +19,8 @@ package framework
 import (
 	"errors"
 	"fmt"
+	"sort"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -89,6 +91,39 @@ type WeightedAffinityTerm struct {
 	Weight int32
 }
 
+// FitError describes a fit error of a pod.
+type FitError struct {
+	Pod                   *v1.Pod
+	NumAllNodes           int
+	FilteredNodesStatuses NodeToStatusMap
+}
+
+const (
+	// NoNodeAvailableMsg is used to format message when no nodes available.
+	NoNodeAvailableMsg = "0/%v nodes are available"
+)
+
+// Error returns detailed information of why the pod failed to fit on each node
+func (f *FitError) Error() string {
+	reasons := make(map[string]int)
+	for _, status := range f.FilteredNodesStatuses {
+		for _, reason := range status.Reasons() {
+			reasons[reason]++
+		}
+	}
+
+	sortReasonsHistogram := func() []string {
+		var reasonStrings []string
+		for k, v := range reasons {
+			reasonStrings = append(reasonStrings, fmt.Sprintf("%v %v", v, k))
+		}
+		sort.Strings(reasonStrings)
+		return reasonStrings
+	}
+	reasonMsg := fmt.Sprintf(NoNodeAvailableMsg+": %v.", f.NumAllNodes, strings.Join(sortReasonsHistogram(), ", "))
+	return reasonMsg
+}
+
 func newAffinityTerm(pod *v1.Pod, term *v1.PodAffinityTerm) (*AffinityTerm, error) {
 	namespaces := schedutil.GetNamespacesFromPodAffinityTerm(pod, term)
 	selector, err := metav1.LabelSelectorAsSelector(term.LabelSelector)

pkg/scheduler/scheduler.go

@@ -457,7 +457,7 @@ func (sched *Scheduler) scheduleOne(ctx context.Context) {
 		// will fit due to the preemption. It is also possible that a different pod will schedule
 		// into the resources that were preempted, but this is harmless.
 		nominatedNode := ""
-		if fitError, ok := err.(*core.FitError); ok {
+		if fitError, ok := err.(*framework.FitError); ok {
 			if !fwk.HasPostFilterPlugins() {
 				klog.V(3).InfoS("No PostFilter plugins are registered, so no preemption will be performed")
 			} else {

pkg/scheduler/scheduler_test.go

@@ -633,7 +633,7 @@ func TestSchedulerNoPhantomPodAfterDelete(t *testing.T) {
 	scheduler.scheduleOne(context.Background())
 	select {
 	case err := <-errChan:
-		expectErr := &core.FitError{
+		expectErr := &framework.FitError{
 			Pod:         secondPod,
 			NumAllNodes: 1,
 			FilteredNodesStatuses: framework.NodeToStatusMap{
@@ -777,7 +777,7 @@ func TestSchedulerFailedSchedulingReasons(t *testing.T) {
 	scheduler.scheduleOne(context.Background())
 	select {
 	case err := <-errChan:
-		expectErr := &core.FitError{
+		expectErr := &framework.FitError{
 			Pod:                   podWithTooBigResourceRequests,
 			NumAllNodes:           len(nodes),
 			FilteredNodesStatuses: failedNodeStatues,