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https://issues.apache.org/jira/browse/HBASE-7509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14157416#comment-14157416
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Jonathan Hsieh commented on HBASE-7509:
---------------------------------------
I believe this can be closed. Reopen if I am wrong.
When using hadoop 2.4 we should just need to include the configs from the
HDFS-5776 release notes in the hbase-site.xml file:
{quote}
This feature is off by default. To enable this feature, set
<code>dfs.client.hedged.read.threadpool.size</code> to a positive number. The
threadpool size is how many threads to dedicate to the running of these
'hedged', concurrent reads in your client.
Then set <code>dfs.client.hedged.read.threshold.millis</code> to the number of
milliseconds to wait before starting up a 'hedged' read. For example, if you
set this property to 10, then if a read has not returned within 10
milliseconds, we will start up a new read against a different block replica.
This feature emits new metrics:
+ hedgedReadOps
+ hedgeReadOpsWin -- how many times the hedged read 'beat' the original read
+ hedgedReadOpsInCurThread -- how many times we went to do a hedged read but we
had to run it in the current thread because
dfs.client.hedged.read.threadpool.size was at a maximum.
{quote}
> Enable RS to query a secondary datanode in parallel, if the primary takes too
> long
> ----------------------------------------------------------------------------------
>
> Key: HBASE-7509
> URL: https://issues.apache.org/jira/browse/HBASE-7509
> Project: HBase
> Issue Type: Improvement
> Reporter: Amitanand Aiyer
> Assignee: Amitanand Aiyer
> Priority: Critical
> Attachments: quorumDiffs.tgz
>
>
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