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https://issues.apache.org/jira/browse/HBASE-5877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13267841#comment-13267841
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Zhihong Yu commented on HBASE-5877:
-----------------------------------
{code}
+ HRegionLocation newHrl = new HRegionLocation(hrl.getRegionInfo(),
hostname, port);
+ if (newHrl == null ){
+ // Should not happened. Just in case.
{code}
Under what condition would newHrl be null above ?
Please remove the space between newHrl and ')' below:
{code}
+ cacheLocation(hrl.getRegionInfo().getTableName(), newHrl );
{code}
For updateCachedLocations():
{code}
+ hrl : getCachedLocation(tableName, row.getRow()));
{code}
Would the above code result in NPE since I see the following in javadoc:
{code}
+ * @param row - can be null if hrl is not null.
{code}
More review comments to follow.
> 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, 5877.v12.patch, 5877.v6.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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