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https://issues.apache.org/jira/browse/HDFS-10702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Mackrory updated HDFS-10702:
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Attachment: HDFS-10702.008.patch
Rebasing patch on more recent changes. I had also discovered that one of the
tests was failing - if you disable stale reads client-side and a fail-over
happens before a write-operation, you still might hit a standby namenode and
the server might still return a response. I did a quick fix by also setting the
minimum txId to Long.MAX_VALUE. Not sure that's how I want to fix it: it means
anyone would have to reset the txId when enabling (although in practice I doubt
that's a problem, as long as they know they have to, and I doubt that will be a
common use case).
I'm going to look at how best to address the potential getBlockLocations issue
as well.
> Add a Client API and Proxy Provider to enable stale read from Standby
> ---------------------------------------------------------------------
>
> Key: HDFS-10702
> URL: https://issues.apache.org/jira/browse/HDFS-10702
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Jiayi Zhou
> Assignee: Sean Mackrory
> Priority: Minor
> Attachments: HDFS-10702.001.patch, HDFS-10702.002.patch,
> HDFS-10702.003.patch, HDFS-10702.004.patch, HDFS-10702.005.patch,
> HDFS-10702.006.patch, HDFS-10702.007.patch, HDFS-10702.008.patch,
> StaleReadfromStandbyNN.pdf
>
>
> Currently, clients must always talk to the active NameNode when performing
> any metadata operation, which means active NameNode could be a bottleneck for
> scalability. One way to solve this problem is to send read-only operations to
> Standby NameNode. The disadvantage is that it might be a stale read.
> Here, I'm thinking of adding a Client API to enable/disable stale read from
> Standby which gives Client the power to set the staleness restriction.
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