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Stably sort controllerrevisions

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Fixes https://github.com/kubernetes/kubernetes/issues/61998

There are times when multiple "equal" controllerrevisions are created with
the same revision number. When this happens and this is the case for the
largest revision number, the statefulset controller will periodically
select one of the maximal controllerrevisions to be the target of the
underlying statefulset. The selection happens here: https://github.com/kubernetes/kubernetes/blob/master/pkg/controller/statefulset/stateful_set_control.go#L212.
Prior to this change this selection was random as the sort was not
stable, which caused the pods of a stable set to continually roll.
This commit is contained in:
Ryan McNamara 2018-08-01 17:25:37 -07:00
parent 7ac1f8974b
commit 0aae852a3c
2 changed files with 37 additions and 7 deletions
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9
pkg/controller/history/controller_history.go
View File

@ -113,7 +113,7 @@ func HashControllerRevision(revision *apps.ControllerRevision, probe *int32) str
// SortControllerRevisions sorts revisions by their Revision.
func SortControllerRevisions(revisions []*apps.ControllerRevision) {
sort.Sort(byRevision(revisions))
sort.Stable(byRevision(revisions))
}
// EqualRevision returns true if lhs and rhs are either both nil, or both point to non-nil ControllerRevisions that
@ -162,7 +162,14 @@ func (br byRevision) Len() int {
return len(br)
}
// Less breaks ties first by creation timestamp, then by name
func (br byRevision) Less(i, j int) bool {
if br[i].Revision == br[j].Revision {
if br[j].CreationTimestamp.Equal(&br[i].CreationTimestamp) {
return br[i].Name < br[j].Name
}
return br[j].CreationTimestamp.After(br[i].CreationTimestamp.Time)
}
return br[i].Revision < br[j].Revision
}

35
pkg/controller/history/controller_history_test.go
View File

@ -40,6 +40,7 @@ import (
"k8s.io/apimachinery/pkg/util/strategicpatch"
core "k8s.io/client-go/testing"
"time"
)
func TestRealHistory_ListControllerRevisions(t *testing.T) {
@ -1545,12 +1546,14 @@ func TestSortControllerRevisions(t *testing.T) {
want []string
}
testFn := func(test *testcase, t *testing.T) {
SortControllerRevisions(test.revisions)
for i := range test.revisions {
if test.revisions[i].Name != test.want[i] {
t.Errorf("%s: want %s at %d got %s", test.name, test.want[i], i, test.revisions[i].Name)
t.Run(test.name, func(t *testing.T) {
SortControllerRevisions(test.revisions)
for i := range test.revisions {
if test.revisions[i].Name != test.want[i] {
t.Errorf("%s: want %s at %d got %s", test.name, test.want[i], i, test.revisions[i].Name)
}
}
}
})
}
ss1 := newStatefulSet(3, "ss1", types.UID("ss1"), map[string]string{"foo": "bar"})
ss1.Status.CollisionCount = new(int32)
@ -1559,17 +1562,32 @@ func TestSortControllerRevisions(t *testing.T) {
if err != nil {
t.Fatal(err)
}
ss1Rev1.Namespace = ss1.Namespace
ss1Rev2, err := NewControllerRevision(ss1, parentKind, ss1.Spec.Template.Labels, rawTemplate(&ss1.Spec.Template), 2, ss1.Status.CollisionCount)
if err != nil {
t.Fatal(err)
}
ss1Rev2.Namespace = ss1.Namespace
ss1Rev3, err := NewControllerRevision(ss1, parentKind, ss1.Spec.Template.Labels, rawTemplate(&ss1.Spec.Template), 3, ss1.Status.CollisionCount)
if err != nil {
t.Fatal(err)
}
ss1Rev3.Namespace = ss1.Namespace
ss1Rev3Time2, err := NewControllerRevision(ss1, parentKind, ss1.Spec.Template.Labels, rawTemplate(&ss1.Spec.Template), 3, ss1.Status.CollisionCount)
if err != nil {
t.Fatal(err)
}
ss1Rev3Time2.Namespace = ss1.Namespace
ss1Rev3Time2.CreationTimestamp = metav1.Time{Time: ss1Rev3.CreationTimestamp.Add(time.Second)}
ss1Rev3Time2Name2, err := NewControllerRevision(ss1, parentKind, ss1.Spec.Template.Labels, rawTemplate(&ss1.Spec.Template), 3, ss1.Status.CollisionCount)
if err != nil {
t.Fatal(err)
}
ss1Rev3Time2Name2.Namespace = ss1.Namespace
ss1Rev3Time2Name2.CreationTimestamp = metav1.Time{Time: ss1Rev3.CreationTimestamp.Add(time.Second)}
tests := []testcase{
{
@ -1587,6 +1605,11 @@ func TestSortControllerRevisions(t *testing.T) {
revisions: []*apps.ControllerRevision{ss1Rev3, ss1Rev2, ss1Rev1},
want: []string{ss1Rev1.Name, ss1Rev2.Name, ss1Rev3.Name},
},
{
name: "with ties",
revisions: []*apps.ControllerRevision{ss1Rev3, ss1Rev3Time2, ss1Rev2, ss1Rev1},
want: []string{ss1Rev1.Name, ss1Rev2.Name, ss1Rev3.Name, ss1Rev3Time2.Name, ss1Rev3Time2Name2.Name},
},
{
name: "empty",
revisions: nil,