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https://issues.apache.org/jira/browse/YARN-2229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14070501#comment-14070501
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Jian He commented on YARN-2229:
-------------------------------

Copied from protobuf guide, changing int32 to int64 seems to be compatible
{code}
int32, uint32, int64, uint64, and bool are all compatible – this means you can 
change a field from one of these types to another without breaking forwards- or 
backwards-compatibility. If a number is parsed from the wire which doesn't fit 
in the corresponding type, you will get the same effect as if you had cast the 
number to that type in C++ (e.g. if a 64-bit number is read as an int32, it 
will be truncated to 32 bits).
{code}

> 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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