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https://issues.apache.org/jira/browse/ZOOKEEPER-1277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13229693#comment-13229693
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Mahadev konar commented on ZOOKEEPER-1277:
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Sorry coming in a little late. Looks good to me as well. Would have wanted to 
avoid the property even though its just for testing. Here is when refactoring 
for testing would have made sense :)
                
> servers stop serving when lower 32bits of zxid roll over
> --------------------------------------------------------
>
>                 Key: ZOOKEEPER-1277
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1277
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: server
>    Affects Versions: 3.3.3
>            Reporter: Patrick Hunt
>            Assignee: Patrick Hunt
>            Priority: Critical
>             Fix For: 3.3.6
>
>         Attachments: ZOOKEEPER-1277_br33.patch, ZOOKEEPER-1277_br33.patch
>
>
> When the lower 32bits of a zxid "roll over" (zxid is a 64 bit number, however 
> the upper 32 are considered the epoch number) the epoch number (upper 32 
> bits) are incremented and the lower 32 start at 0 again.
> This should work fine, however in the current 3.3 branch the followers see 
> this as a NEWLEADER message, which it's not, and effectively stop serving 
> clients. Attached clients seem to eventually time out given that heartbeats 
> (or any operation) are no longer processed. The follower doesn't recover from 
> this.
> I've tested this out on 3.3 branch and confirmed this problem, however I 
> haven't tried it on 3.4/3.5. It may not happen on the newer branches due to 
> ZOOKEEPER-335, however there is certainly an issue with updating the 
> "acceptedEpoch" files contained in the datadir. (I'll enter a separate jira 
> for that)

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