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https://issues.apache.org/jira/browse/HBASE-5877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13261972#comment-13261972
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nkeywal commented on HBASE-5877:
--------------------------------
v1. On an old trunk, so it's just to give an overview. Includes some bits of
HBASE-5844 as well.
There are 3 workarounds in the implementation:
1) As a ServerName is not serializable we use the String dedicated to this kind
of issue. Acceptable I think.
2) hadoop.ipc serialization of exception is based on the #getMessage. So we
have to parse it internally. It's not visisble to the exception user. Still
acceptable (? :-)
3) The code to manage the error in the client package is quite complex. We have
the exception at the very beginning, and then it's checked again, but we don't
have the real exception anymore. I used a new "updateList" to make it works,
I'm looking for another solution here...
> When a query fails because the region has moved, let the regionserver returns
> the new address to the client
> -----------------------------------------------------------------------------------------------------------
>
> Key: HBASE-5877
> URL: https://issues.apache.org/jira/browse/HBASE-5877
> Project: HBase
> Issue Type: Improvement
> Components: client, master, regionserver
> Affects Versions: 0.96.0
> Reporter: nkeywal
> Assignee: nkeywal
> Priority: Minor
> Attachments: 5877.v1.patch
>
>
> This is mainly useful when we do a rolling restart. This will decrease the
> load on the master and the network load.
> Note that a region is not immediately opened after a close. So:
> - it seems preferable to wait before retrying on the other server. An
> optimisation would be to have an heuristic depending on when the region was
> closed.
> - during a rolling restart, the server moves the regions then stops. So we
> may have failures when the server is stopped, and this patch won't help.
> The implementation in the first patch does:
> - on the region move, there is an added parameter on the regionserver#close
> to say where we are sending the region
> - the regionserver keeps a list of what was moved. Each entry is kept 100
> seconds.
> - the regionserver sends a specific exception when it receives a query on a
> moved region. This exception contains the new address.
> - the client analyses the exeptions and update its cache accordingly...
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