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https://issues.apache.org/jira/browse/YARN-1902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14546418#comment-14546418
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Vinod Kumar Vavilapalli commented on YARN-1902:
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bq. Wangda Tan mentioned offline that we could at-least deduct the count
against the over-all number (ANY request) for a given priority.
Further thought tells me this is not desired in some cases as well.
Take the following example.
User originally wants: 1 container on H1, 1 container on H2, and 2 containers
on R1 (rack). The request table becomes
|H1|1|
|H2|1|
|R1|2|
|*|4|
Now assuming RM returns a container on R2 (rack), auto-decrementing the request
table will make it
|H1|1|
|H2|1|
|R1|2|
|*|3|
But user may actually want something like the following. This depends on what
the user preferences are w.r.t scheduling.
|H1|0|
|H2|1|
|R1|2|
|*|3|
> Allocation of too many containers when a second request is done with the same
> resource capability
> -------------------------------------------------------------------------------------------------
>
> Key: YARN-1902
> URL: https://issues.apache.org/jira/browse/YARN-1902
> Project: Hadoop YARN
> Issue Type: Bug
> Components: client
> Affects Versions: 2.2.0, 2.3.0, 2.4.0
> Reporter: Sietse T. Au
> Assignee: Sietse T. Au
> Labels: client
> Attachments: YARN-1902.patch, YARN-1902.v2.patch, YARN-1902.v3.patch
>
>
> Regarding AMRMClientImpl
> Scenario 1:
> Given a ContainerRequest x with Resource y, when addContainerRequest is
> called z times with x, allocate is called and at least one of the z allocated
> containers is started, then if another addContainerRequest call is done and
> subsequently an allocate call to the RM, (z+1) containers will be allocated,
> where 1 container is expected.
> Scenario 2:
> No containers are started between the allocate calls.
> Analyzing debug logs of the AMRMClientImpl, I have found that indeed a (z+1)
> are requested in both scenarios, but that only in the second scenario, the
> correct behavior is observed.
> Looking at the implementation I have found that this (z+1) request is caused
> by the structure of the remoteRequestsTable. The consequence of Map<Resource,
> ResourceRequestInfo> is that ResourceRequestInfo does not hold any
> information about whether a request has been sent to the RM yet or not.
> There are workarounds for this, such as releasing the excess containers
> received.
> The solution implemented is to initialize a new ResourceRequest in
> ResourceRequestInfo when a request has been successfully sent to the RM.
> The patch includes a test in which scenario one is tested.
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