Code change:
<!-- Please use this template while reporting a bug and provide as much info as possible. Not doing so may result in your bug not being addressed in a timely manner. Thanks! If the matter is security related, please disclose it privately via --What happened: I recently saw an issue in which the scheduler hit this log line many times: After some digging, it turns out that PodAffinityChecker has a and . The points at the scheduler's cache instance, while the points at a light wrapper around a . In the scheduler, we use the cache to provide a globally consistent view of the cluster, even if that view is slightly out of date. Data read from the core may not have been processed by the scheduler cache yet. Letting data "skip ahead" like this can cause stale info to get persisted in the scheduler cache, and other subtle bugs. While the original problem is not likely caused by this issue, I think it needs to be cleaned up to avoid potential bugs down the line. What you expected to happen: Predicates should only read state from the scheduler's cache in order to maintain consistency. How to reproduce it (as minimally and precisely as possible): This was observed in a cluster with high rate of pod creation and node creation/deletion. Anything else we need to know?: Environment: Kubernetes version (use ): 1.12.5 Cloud provider or hardware configuration: GKE with preemptible nodes OS (e.g: ): Kernel (e.g. ): Install tools: Others:
/sig scheduling
We do have this kind of issues, and here is another one:
I'm not sure the urgency of this fix, but if its not super urgent, I would love to pick it up, if there's an eng more experienced with the scheduler who could give me some guidance :)
Hi I dug into the source code, and find out is used by the scheduler and kubelet. Maybe we could change the internal struct of , but I do not know why it appears in kubelet which seems irrelevant to the scheduler.
is just a wrapper of corelisters.NodeLister. kubelet can get node info by it.
I think the point is that the kubernetes scheduler was designed to support single instance at the beginning. Even with the addition of multiple scheduler support, the cache between each scheduler is isolated. So at this stage, we can accept this without a shared state solution. After all, the node information is not actively modified by the kubernetes scheduler.
So is it necessary to ensure the consistency by using node lister instead of cache in the scheduler, or we do not need to fix this issue which seems like to caused by inconsistent cache.
We've recently hit this issue with the scheduler. It appears that our scheduler somehow gets out of sync with the nodes, and start scheduling pods on tainted nodes. The node's kubelet then (rightfully) refuse to admit the pod. Looking at the scheduler logs, they are flooded with the following : Similar scenario, this is a high churn cluster with thousands of pods scheduled per minute - and nodes being autoscaled. Can we try to get a fix ?
I'm glad to pick this up if we decide to fix this issue.
It would be awesome if you could fix this issue for us, we are currently seeing 100's of pods incorrectly being scheduled onto nodes with taints.
The code cited for logging "Node not found, %v" is now in :
/assign
Thanks for the interest on fixing this bug. Sorry I haven't had time to engage on this issue. Feel free to send PRs my way. I'm not 100% certain that this will fix the problem of pods getting scheduled to tainted nodes. How is the taint being applied to the node? Even if the scheduler is internally consistent, there could be a time between node creation and the taint being applied where we send pods to that node.

Related discussion:
text: func (cache *schedulerCache) NodeTree() *NodeTree { return cache.nodeTree } <ins> // GetNodeInfo returns cached data for the node name. func (cache *schedulerCache) GetNodeInfo(nodeName string) (*v1.Node, error) { cache.mu.RLock() defer cache.mu.RUnlock() n, ok := cache.nodes[nodeName] if !ok { return nil, fmt.Errorf("error retrieving node '%v' from cache", nodeName) } return n.info.Node(), nil } </ins>