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Posted to yarn-issues@hadoop.apache.org by "Wangda Tan (JIRA)" <ji...@apache.org> on 2018/05/11 00:39:00 UTC
[jira] [Commented] (YARN-8149) Revisit behavior of Re-Reservation
in Capacity Scheduler
[ https://issues.apache.org/jira/browse/YARN-8149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16471327#comment-16471327 ]
Wangda Tan commented on YARN-8149:
----------------------------------
According to previous discussion, downgrade priority and removed 3.1.1 from target version.
> Revisit behavior of Re-Reservation in Capacity Scheduler
> --------------------------------------------------------
>
> Key: YARN-8149
> URL: https://issues.apache.org/jira/browse/YARN-8149
> Project: Hadoop YARN
> Issue Type: Bug
> Reporter: Wangda Tan
> Priority: Major
>
> Frankly speaking, I'm not sure why we need the re-reservation. The formula is not that easy to understand:
> Inside: {{org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.allocator.RegularContainerAllocator#shouldAllocOrReserveNewContainer}}
> {code:java}
> starvation = re-reservation / (#reserved-container *
> (1 - min(requested-resource / max-alloc,
> max-alloc - min-alloc / max-alloc))
> should_allocate = starvation + requiredContainers - reservedContainers > 0{code}
> I think we should be able to remove the starvation computation, just to check requiredContainers > reservedContainers should be enough.
> In a large cluster, we can easily overflow re-reservation to MAX_INT, see YARN-7636.
>
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