/
preemption.go
595 lines (543 loc) · 22.7 KB
/
preemption.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
/*
Copyright 2021 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package preemption
import (
"context"
"errors"
"fmt"
"math"
"sync"
"sync/atomic"
v1 "k8s.io/api/core/v1"
policy "k8s.io/api/policy/v1"
"k8s.io/apimachinery/pkg/labels"
utilerrors "k8s.io/apimachinery/pkg/util/errors"
corelisters "k8s.io/client-go/listers/core/v1"
policylisters "k8s.io/client-go/listers/policy/v1"
corev1helpers "k8s.io/component-helpers/scheduling/corev1"
"k8s.io/klog/v2"
extenderv1 "k8s.io/kube-scheduler/extender/v1"
"k8s.io/kubernetes/pkg/scheduler/framework"
"k8s.io/kubernetes/pkg/scheduler/metrics"
"k8s.io/kubernetes/pkg/scheduler/util"
)
// Candidate represents a nominated node on which the preemptor can be scheduled,
// along with the list of victims that should be evicted for the preemptor to fit the node.
type Candidate interface {
// Victims wraps a list of to-be-preempted Pods and the number of PDB violation.
Victims() *extenderv1.Victims
// Name returns the target node name where the preemptor gets nominated to run.
Name() string
}
type candidate struct {
victims *extenderv1.Victims
name string
}
// Victims returns s.victims.
func (s *candidate) Victims() *extenderv1.Victims {
return s.victims
}
// Name returns s.name.
func (s *candidate) Name() string {
return s.name
}
type candidateList struct {
idx int32
items []Candidate
}
func newCandidateList(size int32) *candidateList {
return &candidateList{idx: -1, items: make([]Candidate, size)}
}
// add adds a new candidate to the internal array atomically.
func (cl *candidateList) add(c *candidate) {
if idx := atomic.AddInt32(&cl.idx, 1); idx < int32(len(cl.items)) {
cl.items[idx] = c
}
}
// size returns the number of candidate stored. Note that some add() operations
// might still be executing when this is called, so care must be taken to
// ensure that all add() operations complete before accessing the elements of
// the list.
func (cl *candidateList) size() int32 {
n := atomic.LoadInt32(&cl.idx) + 1
if n >= int32(len(cl.items)) {
n = int32(len(cl.items))
}
return n
}
// get returns the internal candidate array. This function is NOT atomic and
// assumes that all add() operations have been completed.
func (cl *candidateList) get() []Candidate {
return cl.items[:cl.size()]
}
// Interface is expected to be implemented by different preemption plugins as all those member
// methods might have different behavior compared with the default preemption.
type Interface interface {
// GetOffsetAndNumCandidates chooses a random offset and calculates the number of candidates that should be
// shortlisted for dry running preemption.
GetOffsetAndNumCandidates(nodes int32) (int32, int32)
// CandidatesToVictimsMap builds a map from the target node to a list of to-be-preempted Pods and the number of PDB violation.
CandidatesToVictimsMap(candidates []Candidate) map[string]*extenderv1.Victims
// PodEligibleToPreemptOthers determines whether this pod should be considered
// for preempting other pods or not.
PodEligibleToPreemptOthers(pod *v1.Pod, nominatedNodeStatus *framework.Status) bool
// SelectVictimsOnNode finds minimum set of pods on the given node that should be preempted in order to make enough room
// for "pod" to be scheduled.
// Note that both `state` and `nodeInfo` are deep copied.
SelectVictimsOnNode(ctx context.Context, state *framework.CycleState,
pod *v1.Pod, nodeInfo *framework.NodeInfo, pdbs []*policy.PodDisruptionBudget) ([]*v1.Pod, int, *framework.Status)
}
type Evaluator struct {
PluginName string
Handler framework.Handle
PodLister corelisters.PodLister
PdbLister policylisters.PodDisruptionBudgetLister
State *framework.CycleState
Interface
}
// Preempt returns a PostFilterResult carrying suggested nominatedNodeName, along with a Status.
// The semantics of returned <PostFilterResult, Status> varies on different scenarios:
//
// - <nil, Error>. This denotes it's a transient/rare error that may be self-healed in future cycles.
//
// - <nil, Unschedulable>. This status is mostly as expected like the preemptor is waiting for the
// victims to be fully terminated.
//
// - In both cases above, a nil PostFilterResult is returned to keep the pod's nominatedNodeName unchanged.
//
// - <non-nil PostFilterResult, Unschedulable>. It indicates the pod cannot be scheduled even with preemption.
// In this case, a non-nil PostFilterResult is returned and result.NominatingMode instructs how to deal with
// the nominatedNodeName.
//
// - <non-nil PostFilterResult}, Success>. It's the regular happy path
// and the non-empty nominatedNodeName will be applied to the preemptor pod.
func (ev *Evaluator) Preempt(ctx context.Context, pod *v1.Pod, m framework.NodeToStatusMap) (*framework.PostFilterResult, *framework.Status) {
// 0) Fetch the latest version of <pod>.
// It's safe to directly fetch pod here. Because the informer cache has already been
// initialized when creating the Scheduler obj, i.e., factory.go#MakeDefaultErrorFunc().
// However, tests may need to manually initialize the shared pod informer.
podNamespace, podName := pod.Namespace, pod.Name
pod, err := ev.PodLister.Pods(pod.Namespace).Get(pod.Name)
if err != nil {
klog.ErrorS(err, "Getting the updated preemptor pod object", "pod", klog.KRef(podNamespace, podName))
return nil, framework.AsStatus(err)
}
// 1) Ensure the preemptor is eligible to preempt other pods.
if !ev.PodEligibleToPreemptOthers(pod, m[pod.Status.NominatedNodeName]) {
klog.V(5).InfoS("Pod is not eligible for more preemption", "pod", klog.KObj(pod))
return nil, framework.NewStatus(framework.Unschedulable)
}
// 2) Find all preemption candidates.
candidates, nodeToStatusMap, err := ev.findCandidates(ctx, pod, m)
if err != nil && len(candidates) == 0 {
return nil, framework.AsStatus(err)
}
// Return a FitError only when there are no candidates that fit the pod.
if len(candidates) == 0 {
fitError := &framework.FitError{
Pod: pod,
NumAllNodes: len(nodeToStatusMap),
Diagnosis: framework.Diagnosis{
NodeToStatusMap: nodeToStatusMap,
// Leave FailedPlugins as nil as it won't be used on moving Pods.
},
}
// Specify nominatedNodeName to clear the pod's nominatedNodeName status, if applicable.
return framework.NewPostFilterResultWithNominatedNode(""), framework.NewStatus(framework.Unschedulable, fitError.Error())
}
// 3) Interact with registered Extenders to filter out some candidates if needed.
candidates, status := ev.callExtenders(pod, candidates)
if !status.IsSuccess() {
return nil, status
}
// 4) Find the best candidate.
bestCandidate := ev.SelectCandidate(candidates)
if bestCandidate == nil || len(bestCandidate.Name()) == 0 {
return nil, framework.NewStatus(framework.Unschedulable)
}
// 5) Perform preparation work before nominating the selected candidate.
if status := ev.prepareCandidate(bestCandidate, pod, ev.PluginName); !status.IsSuccess() {
return nil, status
}
return framework.NewPostFilterResultWithNominatedNode(bestCandidate.Name()), framework.NewStatus(framework.Success)
}
// FindCandidates calculates a slice of preemption candidates.
// Each candidate is executable to make the given <pod> schedulable.
func (ev *Evaluator) findCandidates(ctx context.Context, pod *v1.Pod, m framework.NodeToStatusMap) ([]Candidate, framework.NodeToStatusMap, error) {
allNodes, err := ev.Handler.SnapshotSharedLister().NodeInfos().List()
if err != nil {
return nil, nil, err
}
if len(allNodes) == 0 {
return nil, nil, errors.New("no nodes available")
}
potentialNodes, unschedulableNodeStatus := nodesWherePreemptionMightHelp(allNodes, m)
if len(potentialNodes) == 0 {
klog.V(3).InfoS("Preemption will not help schedule pod on any node", "pod", klog.KObj(pod))
// In this case, we should clean-up any existing nominated node name of the pod.
if err := util.ClearNominatedNodeName(ev.Handler.ClientSet(), pod); err != nil {
klog.ErrorS(err, "Cannot clear 'NominatedNodeName' field of pod", "pod", klog.KObj(pod))
// We do not return as this error is not critical.
}
return nil, unschedulableNodeStatus, nil
}
pdbs, err := getPodDisruptionBudgets(ev.PdbLister)
if err != nil {
return nil, nil, err
}
offset, numCandidates := ev.GetOffsetAndNumCandidates(int32(len(potentialNodes)))
if klog.V(5).Enabled() {
var sample []string
for i := offset; i < offset+10 && i < int32(len(potentialNodes)); i++ {
sample = append(sample, potentialNodes[i].Node().Name)
}
klog.InfoS("Selecting candidates from a pool of nodes", "potentialNodesCount", len(potentialNodes), "offset", offset, "sampleLength", len(sample), "sample", sample, "candidates", numCandidates)
}
candidates, nodeStatuses, err := ev.DryRunPreemption(ctx, pod, potentialNodes, pdbs, offset, numCandidates)
for node, nodeStatus := range unschedulableNodeStatus {
nodeStatuses[node] = nodeStatus
}
return candidates, nodeStatuses, err
}
// callExtenders calls given <extenders> to select the list of feasible candidates.
// We will only check <candidates> with extenders that support preemption.
// Extenders which do not support preemption may later prevent preemptor from being scheduled on the nominated
// node. In that case, scheduler will find a different host for the preemptor in subsequent scheduling cycles.
func (ev *Evaluator) callExtenders(pod *v1.Pod, candidates []Candidate) ([]Candidate, *framework.Status) {
extenders := ev.Handler.Extenders()
nodeLister := ev.Handler.SnapshotSharedLister().NodeInfos()
if len(extenders) == 0 {
return candidates, nil
}
// Migrate candidate slice to victimsMap to adapt to the Extender interface.
// It's only applicable for candidate slice that have unique nominated node name.
victimsMap := ev.CandidatesToVictimsMap(candidates)
if len(victimsMap) == 0 {
return candidates, nil
}
for _, extender := range extenders {
if !extender.SupportsPreemption() || !extender.IsInterested(pod) {
continue
}
nodeNameToVictims, err := extender.ProcessPreemption(pod, victimsMap, nodeLister)
if err != nil {
if extender.IsIgnorable() {
klog.InfoS("Skipping extender as it returned error and has ignorable flag set",
"extender", extender, "err", err)
continue
}
return nil, framework.AsStatus(err)
}
// Check if the returned victims are valid.
for nodeName, victims := range nodeNameToVictims {
if victims == nil || len(victims.Pods) == 0 {
if extender.IsIgnorable() {
delete(nodeNameToVictims, nodeName)
klog.InfoS("Ignoring node without victims", "node", klog.KRef("", nodeName))
continue
}
return nil, framework.AsStatus(fmt.Errorf("expected at least one victim pod on node %q", nodeName))
}
}
// Replace victimsMap with new result after preemption. So the
// rest of extenders can continue use it as parameter.
victimsMap = nodeNameToVictims
// If node list becomes empty, no preemption can happen regardless of other extenders.
if len(victimsMap) == 0 {
break
}
}
var newCandidates []Candidate
for nodeName := range victimsMap {
newCandidates = append(newCandidates, &candidate{
victims: victimsMap[nodeName],
name: nodeName,
})
}
return newCandidates, nil
}
// SelectCandidate chooses the best-fit candidate from given <candidates> and return it.
// NOTE: This method is exported for easier testing in default preemption.
func (ev *Evaluator) SelectCandidate(candidates []Candidate) Candidate {
if len(candidates) == 0 {
return nil
}
if len(candidates) == 1 {
return candidates[0]
}
victimsMap := ev.CandidatesToVictimsMap(candidates)
candidateNode := pickOneNodeForPreemption(victimsMap)
// Same as candidatesToVictimsMap, this logic is not applicable for out-of-tree
// preemption plugins that exercise different candidates on the same nominated node.
if victims := victimsMap[candidateNode]; victims != nil {
return &candidate{
victims: victims,
name: candidateNode,
}
}
// We shouldn't reach here.
klog.ErrorS(errors.New("no candidate selected"), "Should not reach here", "candidates", candidates)
// To not break the whole flow, return the first candidate.
return candidates[0]
}
// prepareCandidate does some preparation work before nominating the selected candidate:
// - Evict the victim pods
// - Reject the victim pods if they are in waitingPod map
// - Clear the low-priority pods' nominatedNodeName status if needed
func (ev *Evaluator) prepareCandidate(c Candidate, pod *v1.Pod, pluginName string) *framework.Status {
fh := ev.Handler
cs := ev.Handler.ClientSet()
for _, victim := range c.Victims().Pods {
// If the victim is a WaitingPod, send a reject message to the PermitPlugin.
// Otherwise we should delete the victim.
if waitingPod := fh.GetWaitingPod(victim.UID); waitingPod != nil {
waitingPod.Reject(pluginName, "preempted")
} else if err := util.DeletePod(cs, victim); err != nil {
klog.ErrorS(err, "Preempting pod", "pod", klog.KObj(victim), "preemptor", klog.KObj(pod))
return framework.AsStatus(err)
}
fh.EventRecorder().Eventf(victim, pod, v1.EventTypeNormal, "Preempted", "Preempting", "Preempted by a pod on node %v", c.Name())
}
metrics.PreemptionVictims.Observe(float64(len(c.Victims().Pods)))
// Lower priority pods nominated to run on this node, may no longer fit on
// this node. So, we should remove their nomination. Removing their
// nomination updates these pods and moves them to the active queue. It
// lets scheduler find another place for them.
nominatedPods := getLowerPriorityNominatedPods(fh, pod, c.Name())
if err := util.ClearNominatedNodeName(cs, nominatedPods...); err != nil {
klog.ErrorS(err, "Cannot clear 'NominatedNodeName' field")
// We do not return as this error is not critical.
}
return nil
}
// nodesWherePreemptionMightHelp returns a list of nodes with failed predicates
// that may be satisfied by removing pods from the node.
func nodesWherePreemptionMightHelp(nodes []*framework.NodeInfo, m framework.NodeToStatusMap) ([]*framework.NodeInfo, framework.NodeToStatusMap) {
var potentialNodes []*framework.NodeInfo
nodeStatuses := make(framework.NodeToStatusMap)
for _, node := range nodes {
name := node.Node().Name
// We rely on the status by each plugin - 'Unschedulable' or 'UnschedulableAndUnresolvable'
// to determine whether preemption may help or not on the node.
if m[name].Code() == framework.UnschedulableAndUnresolvable {
nodeStatuses[node.Node().Name] = framework.NewStatus(framework.UnschedulableAndUnresolvable, "Preemption is not helpful for scheduling")
continue
}
potentialNodes = append(potentialNodes, node)
}
return potentialNodes, nodeStatuses
}
func getPodDisruptionBudgets(pdbLister policylisters.PodDisruptionBudgetLister) ([]*policy.PodDisruptionBudget, error) {
if pdbLister != nil {
return pdbLister.List(labels.Everything())
}
return nil, nil
}
// pickOneNodeForPreemption chooses one node among the given nodes. It assumes
// pods in each map entry are ordered by decreasing priority.
// It picks a node based on the following criteria:
// 1. A node with minimum number of PDB violations.
// 2. A node with minimum highest priority victim is picked.
// 3. Ties are broken by sum of priorities of all victims.
// 4. If there are still ties, node with the minimum number of victims is picked.
// 5. If there are still ties, node with the latest start time of all highest priority victims is picked.
// 6. If there are still ties, the first such node is picked (sort of randomly).
// The 'minNodes1' and 'minNodes2' are being reused here to save the memory
// allocation and garbage collection time.
func pickOneNodeForPreemption(nodesToVictims map[string]*extenderv1.Victims) string {
if len(nodesToVictims) == 0 {
return ""
}
minNumPDBViolatingPods := int64(math.MaxInt32)
var minNodes1 []string
lenNodes1 := 0
for node, victims := range nodesToVictims {
numPDBViolatingPods := victims.NumPDBViolations
if numPDBViolatingPods < minNumPDBViolatingPods {
minNumPDBViolatingPods = numPDBViolatingPods
minNodes1 = nil
lenNodes1 = 0
}
if numPDBViolatingPods == minNumPDBViolatingPods {
minNodes1 = append(minNodes1, node)
lenNodes1++
}
}
if lenNodes1 == 1 {
return minNodes1[0]
}
// There are more than one node with minimum number PDB violating pods. Find
// the one with minimum highest priority victim.
minHighestPriority := int32(math.MaxInt32)
var minNodes2 = make([]string, lenNodes1)
lenNodes2 := 0
for i := 0; i < lenNodes1; i++ {
node := minNodes1[i]
victims := nodesToVictims[node]
// highestPodPriority is the highest priority among the victims on this node.
highestPodPriority := corev1helpers.PodPriority(victims.Pods[0])
if highestPodPriority < minHighestPriority {
minHighestPriority = highestPodPriority
lenNodes2 = 0
}
if highestPodPriority == minHighestPriority {
minNodes2[lenNodes2] = node
lenNodes2++
}
}
if lenNodes2 == 1 {
return minNodes2[0]
}
// There are a few nodes with minimum highest priority victim. Find the
// smallest sum of priorities.
minSumPriorities := int64(math.MaxInt64)
lenNodes1 = 0
for i := 0; i < lenNodes2; i++ {
var sumPriorities int64
node := minNodes2[i]
for _, pod := range nodesToVictims[node].Pods {
// We add MaxInt32+1 to all priorities to make all of them >= 0. This is
// needed so that a node with a few pods with negative priority is not
// picked over a node with a smaller number of pods with the same negative
// priority (and similar scenarios).
sumPriorities += int64(corev1helpers.PodPriority(pod)) + int64(math.MaxInt32+1)
}
if sumPriorities < minSumPriorities {
minSumPriorities = sumPriorities
lenNodes1 = 0
}
if sumPriorities == minSumPriorities {
minNodes1[lenNodes1] = node
lenNodes1++
}
}
if lenNodes1 == 1 {
return minNodes1[0]
}
// There are a few nodes with minimum highest priority victim and sum of priorities.
// Find one with the minimum number of pods.
minNumPods := math.MaxInt32
lenNodes2 = 0
for i := 0; i < lenNodes1; i++ {
node := minNodes1[i]
numPods := len(nodesToVictims[node].Pods)
if numPods < minNumPods {
minNumPods = numPods
lenNodes2 = 0
}
if numPods == minNumPods {
minNodes2[lenNodes2] = node
lenNodes2++
}
}
if lenNodes2 == 1 {
return minNodes2[0]
}
// There are a few nodes with same number of pods.
// Find the node that satisfies latest(earliestStartTime(all highest-priority pods on node))
latestStartTime := util.GetEarliestPodStartTime(nodesToVictims[minNodes2[0]])
if latestStartTime == nil {
// If the earliest start time of all pods on the 1st node is nil, just return it,
// which is not expected to happen.
klog.ErrorS(errors.New("earliestStartTime is nil for node"), "Should not reach here", "node", klog.KRef("", minNodes2[0]))
return minNodes2[0]
}
nodeToReturn := minNodes2[0]
for i := 1; i < lenNodes2; i++ {
node := minNodes2[i]
// Get earliest start time of all pods on the current node.
earliestStartTimeOnNode := util.GetEarliestPodStartTime(nodesToVictims[node])
if earliestStartTimeOnNode == nil {
klog.ErrorS(errors.New("earliestStartTime is nil for node"), "Should not reach here", "node", klog.KRef("", node))
continue
}
if earliestStartTimeOnNode.After(latestStartTime.Time) {
latestStartTime = earliestStartTimeOnNode
nodeToReturn = node
}
}
return nodeToReturn
}
// getLowerPriorityNominatedPods returns pods whose priority is smaller than the
// priority of the given "pod" and are nominated to run on the given node.
// Note: We could possibly check if the nominated lower priority pods still fit
// and return those that no longer fit, but that would require lots of
// manipulation of NodeInfo and PreFilter state per nominated pod. It may not be
// worth the complexity, especially because we generally expect to have a very
// small number of nominated pods per node.
func getLowerPriorityNominatedPods(pn framework.PodNominator, pod *v1.Pod, nodeName string) []*v1.Pod {
podInfos := pn.NominatedPodsForNode(nodeName)
if len(podInfos) == 0 {
return nil
}
var lowerPriorityPods []*v1.Pod
podPriority := corev1helpers.PodPriority(pod)
for _, pi := range podInfos {
if corev1helpers.PodPriority(pi.Pod) < podPriority {
lowerPriorityPods = append(lowerPriorityPods, pi.Pod)
}
}
return lowerPriorityPods
}
// DryRunPreemption simulates Preemption logic on <potentialNodes> in parallel,
// 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.
// NOTE: This method is exported for easier testing in default preemption.
func (ev *Evaluator) DryRunPreemption(ctx context.Context, pod *v1.Pod, potentialNodes []*framework.NodeInfo,
pdbs []*policy.PodDisruptionBudget, offset int32, numCandidates int32) ([]Candidate, framework.NodeToStatusMap, error) {
fh := ev.Handler
nonViolatingCandidates := newCandidateList(numCandidates)
violatingCandidates := newCandidateList(numCandidates)
parallelCtx, cancel := context.WithCancel(ctx)
defer cancel()
nodeStatuses := make(framework.NodeToStatusMap)
var statusesLock sync.Mutex
var errs []error
checkNode := func(i int) {
nodeInfoCopy := potentialNodes[(int(offset)+i)%len(potentialNodes)].Clone()
stateCopy := ev.State.Clone()
pods, numPDBViolations, status := ev.SelectVictimsOnNode(ctx, stateCopy, pod, nodeInfoCopy, pdbs)
if status.IsSuccess() && len(pods) != 0 {
victims := extenderv1.Victims{
Pods: pods,
NumPDBViolations: int64(numPDBViolations),
}
c := &candidate{
victims: &victims,
name: nodeInfoCopy.Node().Name,
}
if numPDBViolations == 0 {
nonViolatingCandidates.add(c)
} else {
violatingCandidates.add(c)
}
nvcSize, vcSize := nonViolatingCandidates.size(), violatingCandidates.size()
if nvcSize > 0 && nvcSize+vcSize >= numCandidates {
cancel()
}
return
}
if status.IsSuccess() && len(pods) == 0 {
status = framework.AsStatus(fmt.Errorf("expected at least one victim pod on node %q", nodeInfoCopy.Node().Name))
}
statusesLock.Lock()
if status.Code() == framework.Error {
errs = append(errs, status.AsError())
}
nodeStatuses[nodeInfoCopy.Node().Name] = status
statusesLock.Unlock()
}
fh.Parallelizer().Until(parallelCtx, len(potentialNodes), checkNode)
return append(nonViolatingCandidates.get(), violatingCandidates.get()...), nodeStatuses, utilerrors.NewAggregate(errs)
}