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Merge pull request #35294 from wojtek-t/kubelet_get_from_cache

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Automatic merge from submit-queue

Kubelet getting node from apiserver cache before update.

This is blocked on #35218 (however it's ready for review).

It seems to visibly reduce the apiserver metrics (and I didn't observe higher number of conflicts even in 2000-node kubemark).
This commit is contained in:
Kubernetes Submit Queue 2016-10-22 01:59:57 -07:00 committed by GitHub
commit eeae8b5975
1 changed files with 18 additions and 2 deletions
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20
pkg/kubelet/kubelet_node_status.go
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@ -31,6 +31,7 @@ import (
"k8s.io/kubernetes/pkg/api/resource"
"k8s.io/kubernetes/pkg/api/unversioned"
"k8s.io/kubernetes/pkg/cloudprovider"
"k8s.io/kubernetes/pkg/fields"
"k8s.io/kubernetes/pkg/kubelet/cadvisor"
"k8s.io/kubernetes/pkg/kubelet/events"
"k8s.io/kubernetes/pkg/kubelet/util/sliceutils"
@ -309,13 +310,28 @@ func (kl *Kubelet) updateNodeStatus() error {
// tryUpdateNodeStatus tries to update node status to master. If ReconcileCBR0
// is set, this function will also confirm that cbr0 is configured correctly.
func (kl *Kubelet) tryUpdateNodeStatus() error {
node, err := kl.kubeClient.Core().Nodes().Get(string(kl.nodeName))
// In large clusters, GET and PUT operations on Node objects coming
// from here are the majority of load on apiserver and etcd.
// To reduce the load on etcd, we are serving GET operations from
// apiserver cache (the data might be slightly delayed but it doesn't
// seem to cause more confilict - the delays are pretty small).
// TODO: Currently apiserver doesn't support serving GET operations
// from its cache. Thus we are hacking it by issuing LIST with
// field selector for the name of the node (field selectors with
// specified name are handled efficiently by apiserver). Once
// apiserver supports GET from cache, change it here.
opts := api.ListOptions{
FieldSelector: fields.Set{"metadata.name": string(kl.nodeName)}.AsSelector(),
ResourceVersion: "0",
}
nodes, err := kl.kubeClient.Core().Nodes().List(opts)
if err != nil {
return fmt.Errorf("error getting node %q: %v", kl.nodeName, err)
}
if node == nil {
if len(nodes.Items) != 1 {
return fmt.Errorf("no node instance returned for %q", kl.nodeName)
}
node := &nodes.Items[0]
if kl.reconcileCIDR {
kl.updatePodCIDR(node.Spec.PodCIDR)