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https://issues.apache.org/jira/browse/YARN-1424?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14025314#comment-14025314
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Jason Lowe commented on YARN-1424:
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-1 was chosen to explicitly mark the field as having an invalid value to note
that the true value is unknown or inaccessible. For example, having no
reserved containers is a valid state, so how would a client distinguish between
an application having no reservations and the case where we cannot report the
proper value? Similarly unmanaged AMs don't have resource utilization on the
cluster for the AM itself, so an unmanaged AM without any other containers
could show up with zero resource consumption.
I could see it either way -- either clients will blindly sum and assume they
won't need to differentiate apps they can't see details from apps they can, or
clients will want to differentiate and then we need a way to convey that. If
we do change to using zeroes then technically this would be an incompatible
change since we would no longer be flagging unreportable/inaccessible values
via the -1 value.
> RMAppAttemptImpl should precompute a zeroed ApplicationResourceUsageReport to
> return when attempt not active
> ------------------------------------------------------------------------------------------------------------
>
> Key: YARN-1424
> URL: https://issues.apache.org/jira/browse/YARN-1424
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: resourcemanager
> Affects Versions: 2.4.0
> Reporter: Sandy Ryza
> Assignee: Ray Chiang
> Priority: Minor
> Labels: newbie
> Attachments: YARN1424-01.patch, YARN1424-02.patch
>
>
> RMAppImpl has a DUMMY_APPLICATION_RESOURCE_USAGE_REPORT to return when the
> caller of createAndGetApplicationReport doesn't have access.
> RMAppAttemptImpl should have something similar for
> getApplicationResourceUsageReport.
> It also might make sense to put the dummy report into
> ApplicationResourceUsageReport and allow both to use it.
> A test would also be useful to verify that
> RMAppAttemptImpl#getApplicationResourceUsageReport doesn't return null if the
> scheduler doesn't have a report to return.
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