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Fix a preemption bug when pods are listed in pdb.Status.DisruptedPods #92476

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Jun 25, 2020
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Fix a preemption bug when pods are listed in pdb.Status.DisruptedPods #92476

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4886218
Fix a preemption bug when pods are matched by pdb.Status.DisruptedPods
Huang-Wei Jun 24, 2020
82ab6db
Pods in pdb.Status.DisruptedPods are treated as 'nonViolating' in any…
Huang-Wei Jun 24, 2020
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17 changes: 10 additions & 7 deletions pkg/scheduler/core/generic_scheduler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -936,15 +936,18 @@ func filterPodsWithPDBViolation(pods []*v1.Pod, pdbs []*policy.PodDisruptionBudg
if selector.Empty() || !selector.Matches(labels.Set(pod.Labels)) {
continue
}

// Existing in DisruptedPods means it has been processed in API server,
// we don't treat it as a violating case.
if _, exist := pdb.Status.DisruptedPods[pod.Name]; exist {
continue
}
// Only decrement the matched pdb when it's not in its <DisruptedPods>;
// otherwise we may over-decrement the budget number.
pdbsAllowed[i]--
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wouldn't this make the value go into the minus? I guess it doesn't matter if that happens, right?

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Yes, pdbsAllowed[i] can be negative now.

Another style is like this:

if pdbsAllowed[i] <= 0 {
    pdbForPodIsViolated = true
} else {
    pdbsAllowed[i]--
}

Not quite make a big difference I think :)

// We have found a matching PDB.
if pdbsAllowed[i] <= 0 {
if pdbsAllowed[i] < 0 {
pdbForPodIsViolated = true
} else {
// Only decrement the matched pdb when it's not in its <DisruptedPods>;
// otherwise we may over-decrement the budget number.
if _, exist := pdb.Status.DisruptedPods[pod.Name]; !exist {
pdbsAllowed[i]--
}
}
}
}
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20 changes: 19 additions & 1 deletion pkg/scheduler/core/generic_scheduler_test.go
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Expand Up @@ -1496,10 +1496,28 @@ func TestSelectNodesForPreemption(t *testing.T) {
{ObjectMeta: metav1.ObjectMeta{Name: "a", UID: types.UID("a"), Labels: map[string]string{"app": "foo"}}, Spec: v1.PodSpec{Containers: mediumContainers, Priority: &midPriority, NodeName: "machine1"}},
{ObjectMeta: metav1.ObjectMeta{Name: "b", UID: types.UID("b"), Labels: map[string]string{"app": "foo"}}, Spec: v1.PodSpec{Containers: mediumContainers, Priority: &midPriority, NodeName: "machine1"}}},
pdbs: []*policy.PodDisruptionBudget{
{Spec: policy.PodDisruptionBudgetSpec{Selector: &metav1.LabelSelector{MatchLabels: map[string]string{"app": "foo"}}}, Status: policy.PodDisruptionBudgetStatus{DisruptionsAllowed: 1, DisruptedPods: map[string]metav1.Time{"a": {Time: time.Now()}}}}},
{Spec: policy.PodDisruptionBudgetSpec{Selector: &metav1.LabelSelector{MatchLabels: map[string]string{"app": "foo"}}}, Status: policy.PodDisruptionBudgetStatus{DisruptionsAllowed: 1, DisruptedPods: map[string]metav1.Time{"b": {Time: time.Now()}}}}},
expected: map[string]victims{"machine1": {pods: sets.NewString("a", "b"), numPDBViolations: 0}},
expectedNumFilterCalled: 3,
},
{
name: "preemption with violation of the pdb with pod whose eviction was processed, the victim which belongs to DisruptedPods is treated as 'nonViolating'",
registerPlugins: []st.RegisterPluginFunc{
st.RegisterQueueSortPlugin(queuesort.Name, queuesort.New),
st.RegisterPluginAsExtensions(noderesources.FitName, noderesources.NewFit, "Filter", "PreFilter"),
st.RegisterBindPlugin(defaultbinder.Name, defaultbinder.New),
},
nodes: []string{"machine1"},
pod: &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "pod1", UID: types.UID("pod1")}, Spec: v1.PodSpec{Containers: veryLargeContainers, Priority: &highPriority}},
pods: []*v1.Pod{
{ObjectMeta: metav1.ObjectMeta{Name: "a", UID: types.UID("a"), Labels: map[string]string{"app": "foo"}}, Spec: v1.PodSpec{Containers: mediumContainers, Priority: &midPriority, NodeName: "machine1"}},
{ObjectMeta: metav1.ObjectMeta{Name: "b", UID: types.UID("b"), Labels: map[string]string{"app": "foo"}}, Spec: v1.PodSpec{Containers: mediumContainers, Priority: &midPriority, NodeName: "machine1"}},
{ObjectMeta: metav1.ObjectMeta{Name: "c", UID: types.UID("c"), Labels: map[string]string{"app": "foo"}}, Spec: v1.PodSpec{Containers: mediumContainers, Priority: &midPriority, NodeName: "machine1"}}},
pdbs: []*policy.PodDisruptionBudget{
{Spec: policy.PodDisruptionBudgetSpec{Selector: &metav1.LabelSelector{MatchLabels: map[string]string{"app": "foo"}}}, Status: policy.PodDisruptionBudgetStatus{DisruptionsAllowed: 1, DisruptedPods: map[string]metav1.Time{"c": {Time: time.Now()}}}}},
expected: map[string]victims{"machine1": {pods: sets.NewString("a", "b", "c"), numPDBViolations: 1}},
expectedNumFilterCalled: 4,
},
}
labelKeys := []string{"hostname", "zone", "region"}
for _, test := range tests {
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