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From "Colin Patrick McCabe (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (YARN-2327) YARN should warn about nodes with poor clock synchronization
Date Mon, 21 Jul 2014 18:14:41 GMT

     [ https://issues.apache.org/jira/browse/YARN-2327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Colin Patrick McCabe updated YARN-2327:
---------------------------------------

    Description: 
YARN should warn about nodes with poor clock synchronization.

YARN statistics rely on approximate clock synchronization in a few cases (see YARN-2251),
but we currently don't warn if this assumption is violated.

  was:
As a distributed system, a hadoop cluster wants the clock on all the participating hosts synchronized.
Otherwise, some problems might happen. For example, in YARN-2251, due to the clock on the
host for the task container falls behind that on the host of the AM container, the computed
elapsed time (the diff between the timestamps produced on two hosts) becomes negative.

In YARN-2251, we tried to mask the negative elapsed time. However, we should seek for a decent
long term solution, such as providing mechanism to do and check clock synchronization.


> YARN should warn about nodes with poor clock synchronization
> ------------------------------------------------------------
>
>                 Key: YARN-2327
>                 URL: https://issues.apache.org/jira/browse/YARN-2327
>             Project: Hadoop YARN
>          Issue Type: Bug
>            Reporter: Zhijie Shen
>
> YARN should warn about nodes with poor clock synchronization.
> YARN statistics rely on approximate clock synchronization in a few cases (see YARN-2251),
but we currently don't warn if this assumption is violated.



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