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https://issues.apache.org/jira/browse/HBASE-5877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13262462#comment-13262462
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nkeywal commented on HBASE-5877:
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bq. Can we mark the failure and make this RegionMovedException behave the same
as NotServingRegionException ?
Done.
bq. For updateCachedLocations(), please put explanation for parameter on the
same line as the parameter:
Done.
bq. 'Failed all' -> 'Failed call'
It's an existing comment that we can find again later in the code. It really
means "failed all": all the queries on this server failed. I don't mind
changing it to something better, but I think we should keep the "all".
bq. 'which the server' -> 'which the region'
Done.
bq. Please increase the VERSION of HRegionInterface
Done.
bq. How is the server removed from cache since I see 'continue' above ?
That's what makes this code complex and difficult to change: the error is
actually managed later, when we don't have the real exception anymore.
bq. For ServerManager.sendRegionClose(), please add javadoc for destServerName
param.
Done.
bq. Is it possible that destServerName is null ?
Safety checks added.
bq. Please change the above to debug log. && Why is the above fatal
(regionResult != null) ? Step 4 appears in a comment below the above code.
Should the above say step 3 ?
Bad logs fixed.
> When a query fails because the region has moved, let the regionserver return
> 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
> Fix For: 0.96.0
>
> 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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