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https://issues.apache.org/jira/browse/YARN-8149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16435550#comment-16435550
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Weiwei Yang edited comment on YARN-8149 at 4/13/18 2:17 AM:
------------------------------------------------------------
Hi [~leftnoteasy]
I am not sure if it is a good idea to remove this since this is some legend
code there for years, looks like was added in MAPREDUCE-2917. The original
formular was
{code}
starvation = (int)((application.getReReservations(priority) /
reservedContainers) * + absoluteCapacity);
{code}
was (Author: cheersyang):
Hi [~leftnoteasy]
I am sure if it is a good idea to remove this since this is some legend code
there for years, looks like was added in MAPREDUCE-2917. The original formular
was
{code}
starvation = (int)((application.getReReservations(priority) /
reservedContainers) * + absoluteCapacity);
{code}
> 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: Critical
>
> 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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