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From "Jian He (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-1372) Ensure all completed containers are reported to the AMs across RM restart
Date Wed, 27 Aug 2014 20:56:59 GMT

    [ https://issues.apache.org/jira/browse/YARN-1372?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14112830#comment-14112830

Jian He commented on YARN-1372:

bq. I looked into an alternate approach where the RM acks the completed containers that belong
to an App thats completed.
Can you please elaborate the changes you made for this approach ? By looking at the diffs
of patches, seems the following change is what you are referring to. 
// Ack all previousJustFinishedContainers and justFinishedContainers to NM
(why call the same method twice ?) This may not guarantee notifying NM to clean all containers
from context, because a) containers may not yet finish at this point; b) containers finished
but not yet added to the list(in transit) will not be notified.

bq.  Next allocate call from AM has happened after the container was sent. This implicitly
acks from AM point of view and now can be sent to NM.
Can we ack NMs at the same time when the finishedContainers are pulled by AM? In the current
patch, when AM calls allocate, justFinishedContainers will be transferred to previousJustFinishedContainers.
  If AM never calls allocate again, those containers in previousJustFinishedContainers will
not be notified to NM.

> Ensure all completed containers are reported to the AMs across RM restart
> -------------------------------------------------------------------------
>                 Key: YARN-1372
>                 URL: https://issues.apache.org/jira/browse/YARN-1372
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: resourcemanager
>            Reporter: Bikas Saha
>            Assignee: Anubhav Dhoot
>         Attachments: YARN-1372.001.patch, YARN-1372.001.patch, YARN-1372.002_NMHandlesCompletedApp.patch,
YARN-1372.002_RMHandlesCompletedApp.patch, YARN-1372.002_RMHandlesCompletedApp.patch, YARN-1372.prelim.patch,
> Currently the NM informs the RM about completed containers and then removes those containers
from the RM notification list. The RM passes on that completed container information to the
AM and the AM pulls this data. If the RM dies before the AM pulls this data then the AM may
not be able to get this information again. To fix this, NM should maintain a separate list
of such completed container notifications sent to the RM. After the AM has pulled the containers
from the RM then the RM will inform the NM about it and the NM can remove the completed container
from the new list. Upon re-register with the RM (after RM restart) the NM should send the
entire list of completed containers to the RM along with any other containers that completed
while the RM was dead. This ensures that the RM can inform the AM's about all completed containers.
Some container completions may be reported more than once since the AM may have pulled the
container but the RM may die before notifying the NM about the pull.

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