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https://issues.apache.org/jira/browse/YARN-2229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14071853#comment-14071853
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Tsuyoshi OZAWA commented on YARN-2229:
--------------------------------------

Thanks for the comments, Jian, Zhijie and Sid.

{quote}
For example, ContainerTokenIdentifier serializes a long (getContainerId()) at 
RM side, but deserializes a int (getId()) at NM side. In this case, I'm afraid 
it's going to be wrong
{quote}

If we think the backward compatibility as first priority, we can choose the 
first design I proposed as Sid mentioned. This design choice looks reasonable 
to me. [~jianhe], what do you think? We discussed that we should avoid 
introducing new field to ContinerId class. In my opinion, this reason is weaker 
than the backward compatibility.

{quote}
ConverterUtils is a separate consideration. It is marked as @private - but is 
used in MapReduce for example (and also in Tez). Looks like the toString method 
isn't being changed either, whcih means to ConverterUtils method would continue 
to work.
{quote}

I'm thinking to suffix the epoch at the end of container id. I'll work with old 
jar which includes old {{ConverterUtils#toContainerId}}. YARN-2182 is the JIRA 
to address the change of {{ConverterUtils#toContainerId}}.



> ContainerId can overflow with RM restart
> ----------------------------------------
>
>                 Key: YARN-2229
>                 URL: https://issues.apache.org/jira/browse/YARN-2229
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: resourcemanager
>            Reporter: Tsuyoshi OZAWA
>            Assignee: Tsuyoshi OZAWA
>         Attachments: YARN-2229.1.patch, YARN-2229.10.patch, 
> YARN-2229.10.patch, YARN-2229.2.patch, YARN-2229.2.patch, YARN-2229.3.patch, 
> YARN-2229.4.patch, YARN-2229.5.patch, YARN-2229.6.patch, YARN-2229.7.patch, 
> YARN-2229.8.patch, YARN-2229.9.patch
>
>
> On YARN-2052, we changed containerId format: upper 10 bits are for epoch, 
> lower 22 bits are for sequence number of Ids. This is for preserving 
> semantics of {{ContainerId#getId()}}, {{ContainerId#toString()}}, 
> {{ContainerId#compareTo()}}, {{ContainerId#equals}}, and 
> {{ConverterUtils#toContainerId}}. One concern is epoch can overflow after RM 
> restarts 1024 times.
> To avoid the problem, its better to make containerId long. We need to define 
> the new format of container Id with preserving backward compatibility on this 
> JIRA.



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