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Juanjuan Tian commented on YARN-9598: -------------------------------------- Hi, [~Tao Yang], just like you said, there will always be one reserved container when re-reservation disabled, and thus even when inter-queue preemption is enabled in cluster, preemption will not happen. But if we can reseve several containers, preemption can be triggered (yarn.resourcemanager.monitor.capacity.preemption.additional_res_balance_based_on_reserved_containers is set to true ) > Make reservation work well when multi-node enabled > -------------------------------------------------- > > Key: YARN-9598 > URL: https://issues.apache.org/jira/browse/YARN-9598 > Project: Hadoop YARN > Issue Type: Bug > Components: capacityscheduler > Reporter: Tao Yang > Assignee: Tao Yang > Priority: Major > Attachments: YARN-9598.001.patch, image-2019-06-10-11-37-43-283.png, > image-2019-06-10-11-37-44-975.png > > > This issue is to solve problems about reservation when multi-node enabled: > # As discussed in YARN-9576, re-reservation proposal may be always generated > on the same node and break the scheduling for this app and later apps. I > think re-reservation in unnecessary and we can replace it with > LOCALITY_SKIPPED to let scheduler have a chance to look up follow candidates > for this app when multi-node enabled. > # Scheduler iterates all nodes and try to allocate for reserved container in > LeafQueue#allocateFromReservedContainer. Here there are two problems: > ** The node of reserved container should be taken as candidates instead of > all nodes when calling FiCaSchedulerApp#assignContainers, otherwise later > scheduler may generate a reservation-fulfilled proposal on another node, > which will always be rejected in FiCaScheduler#commonCheckContainerAllocation. > ** Assignment returned by FiCaSchedulerApp#assignContainers could never be > null even if it's just skipped, it will break the normal scheduling process > for this leaf queue because of the if clause in LeafQueue#assignContainers: > "if (null != assignment) \{ return assignment;}" > # Nodes which have been reserved should be skipped when iterating candidates > in RegularContainerAllocator#allocate, otherwise scheduler may generate > allocation or reservation proposal on these node which will always be > rejected in FiCaScheduler#commonCheckContainerAllocation. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: yarn-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: yarn-issues-h...@hadoop.apache.org