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https://issues.apache.org/jira/browse/HBASE-10278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13926453#comment-13926453
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stack commented on HBASE-10278:
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bq. Interrupt the SyncRunner threads to unblock them from their current sync
call, and wait till they reach a safe point.
Any issues interrupting? I've found interrupting hdfs a PITA or rather, the
variety of exceptions that can come up are many... its tricky figuring which
can be caught and which not.
bq. Set FSHLog#switching true.
Every new append or is it sync must run over this new volatile?
bq. 3) Grab their Append lists (i.e., whatever they were trying to sync).
Consolidate, and sort it. These are the "in-flight" edits we need to append to
the new Writer.
'sort'? We've given these items their seqid at this stage, right? Will the
sort mess this up?
More comments over in rb
> Provide better write predictability
> -----------------------------------
>
> Key: HBASE-10278
> URL: https://issues.apache.org/jira/browse/HBASE-10278
> Project: HBase
> Issue Type: New Feature
> Reporter: Himanshu Vashishtha
> Assignee: Himanshu Vashishtha
> Attachments: 10278-wip-1.1.patch, Multiwaldesigndoc.pdf
>
>
> Currently, HBase has one WAL per region server.
> Whenever there is any latency in the write pipeline (due to whatever reasons
> such as n/w blip, a node in the pipeline having a bad disk, etc), the overall
> write latency suffers.
> Jonathan Hsieh and I analyzed various approaches to tackle this issue. We
> also looked at HBASE-5699, which talks about adding concurrent multi WALs.
> Along with performance numbers, we also focussed on design simplicity,
> minimum impact on MTTR & Replication, and compatibility with 0.96 and 0.98.
> Considering all these parameters, we propose a new HLog implementation with
> WAL Switching functionality.
> Please find attached the design doc for the same. It introduces the WAL
> Switching feature, and experiments/results of a prototype implementation,
> showing the benefits of this feature.
> The second goal of this work is to serve as a building block for concurrent
> multiple WALs feature.
> Please review the doc.
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