[YARN-8804] resourceLimits may be wrongly calculated when leaf-queue is blocked in cluster with 3+ level queues

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 3.2.0
• Fix Version/s: 2.10.0, 3.2.0, 2.9.2, 3.0.4, 3.1.2, 2.8.6
• Component/s: capacityscheduler
• Target Version/s: 2.10.0, 3.2.0, 2.9.2, 3.0.4, 3.1.2, 2.8.6
• Hadoop Flags: Reviewed
• Assignee: Tao Yang
• Reporter: Tao Yang
• Created: 20/Sep/18 07:33
• Updated: 27/Sep/18 03:27
• Resolved: 27/Sep/18 00:26

Description

This problem is due to YARN-4280, parent queue will deduct child queue's headroom when the child queue reached its resource limit and the skipped type is QUEUE_LIMIT, the resource limits of deepest parent queue will be correctly calculated, but for non-deepest parent queue, its headroom may be much more than the sum of reached-limit child queues' headroom, so that the resource limit of non-deepest parent may be much less than its true value and block the allocation for later queues.

To reproduce this problem with UT:
(1) Cluster has two nodes whose node resource both are <10GB, 10core> and 3-level queues as below, among them max-capacity of "c1" is 10 and others are all 100, so that max-capacity of queue "c1" is <2GB, 2core>

                  Root
                 /  |  \
                a   b    c
               10   20   70
                         |   \
                        c1   c2
                  10(max=10) 90

(2) Submit app1 to queue "c1" and launch am1(resource=<1GB, 1 core>) on nm1
(3) Submit app2 to queue "b" and launch am2(resource=<1GB, 1 core>) on nm1
(4) app1 and app2 both ask one <2GB, 1core> containers.
(5) nm1 do 1 heartbeat
Now queue "c" has lower capacity percentage than queue "b", the allocation sequence will be "a" -> "c" -> "b",
queue "c1" has reached queue limit so that requests of app1 should be pending,
headroom of queue "c1" is <1GB, 1core> (=max-capacity - used),
headroom of queue "c" is <18GB, 18core> (=max-capacity - used),
after allocation for queue "c", resource limit of queue "b" will be wrongly calculated as <2GB, 2core>,
headroom of queue "b" will be <1GB, 1core> (=resource-limit - used)
so that scheduler won't allocate one container for app2 on nm1

Issue Links

• is caused by: YARN-4280 CapacityScheduler reservations may not prevent indefinite postponement on a busy cluster