Hi. I have just started using Yunikorn for scheduling with K8s. I have been
doing some simple experiments to make sure I understand how it works. Most of
them are working as expected, but there is one I don't understand.
I used Helm to deploy Yunikorn and I did not modify anything, so I have the
default setup: one queue per namespace, and I assume the application sort
policy is the default of "FifoSortPolicy."
I create four pods. All of them have the resource requests set the same (2
cores, 1Gi mem), and the resource requests are such that only two can run at a
time. The pods are created in this order, with a 1 second gap between each:
1. A-1, applicationId = A, sleeps for 10s
2. A-2, applicationId = A, sleeps for 5s
3. B-1, applicationId = B, sleeps for 5s
4. A-3, applicationId = A, sleeps for 5s
What I expect to see is:
* A-1 is scheduled
* A-2 is scheduled
* A-2 finishes
* A-3 is scheduled (because A is the first application created, as long as
there are pods in the queue for application A I understand that they should
have priority over pods for application B)
What I see instead is that after A-2 finishes, B-1 gets scheduled to run.
Is this the expected behavior, and if so can someone explain what is wrong with
my understanding?
Additionally, in the logs for the scheduler pod, right after pod B-1 gets
scheduled, I see the following messages repeated thousands of times very fast
(over 2000 instances in about .25s according to timestamps in log). Is this
normal?
2021-02-05T20:25:34.479Z DEBUG scheduler/scheduling_application.go:641 skipping
node for allocation: basic condition not satisfied {"node": "local-node",
"allocationKey": "258d9947-e92b-4967-9758-08eee62f4d1b", "error": "pre alloc
check: requested resource map[memory:1074 vcore:2000] is larger than currently
available map[ephemeral-storage:50977832921 hugepages-2Mi:0 memory:13250
pods:110 vcore:1600] resource on local-node"}
2021-02-05T20:25:34.479Z DEBUG scheduler/scheduling_node.go:271 requested
resource is larger than currently available node resources {"nodeID":
"local-node", "requested": "map[memory:1074 vcore:2000]", "available":
"map[ephemeral-storage:50977832921 hugepages-2Mi:0 memory:13250 pods:110
vcore:1600]"}
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