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From "Daniel Templeton (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-4401) A failed app recovery should not prevent the RM from starting
Date Wed, 02 Dec 2015 14:43:10 GMT

    [ https://issues.apache.org/jira/browse/YARN-4401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15035892#comment-15035892
] 

Daniel Templeton commented on YARN-4401:
----------------------------------------

I suppose I posed my proposal a little naively.  Let's try again.

The reason for configuring HA is to prevent an outage.  It should be possible to tell the
standby to come up regardless of recovery failures, in effect performing automatically the
operation that [~sunilg] described or failing the bad app(s) or whatever.

The app resource issue I offered was just the first example I (thought I) found while skimming
the code.  Rather than having to hunt down every possible way to throw an exception (checked
or unchecked) during recovery, it would be convenient to have recovery catch any exception,
log it, and do something sensible so that the RM can come up for cases where RM availability
is a priority.

> A failed app recovery should not prevent the RM from starting
> -------------------------------------------------------------
>
>                 Key: YARN-4401
>                 URL: https://issues.apache.org/jira/browse/YARN-4401
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: resourcemanager
>    Affects Versions: 2.7.1
>            Reporter: Daniel Templeton
>            Assignee: Daniel Templeton
>            Priority: Critical
>         Attachments: YARN-4401.001.patch
>
>
> There are many different reasons why an app recovery could fail with an exception, causing
the RM start to be aborted.  If that happens the RM will fail to start.  Presumably, the reason
the RM is trying to do a recovery is that it's the standby trying to fill in for the active.
 Failing to come up defeats the purpose of the HA configuration.  Instead of preventing the
RM from starting, a failed app recovery should log an error and skip the application.



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