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https://issues.apache.org/jira/browse/HBASE-21394?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17063006#comment-17063006
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Xu Cang commented on HBASE-21394:
---------------------------------
While I am debugging snapshot related issue. I found this JIRA.
>From my observation, this method : RestoreSnapshotHelper#restoreHdfsRegions()
>will always try to iterate all regions and open all hfiles for the table from
>all mappers.
So suppose we have 500 mappers scanning snapshot of the table, all 500 mappers
are iterating all regions/hfiles. Was this the same symptom you saw and was
that by design? (BTW, I am using branch-1 code, haven't tried this parallel
improvements).
[~openinx]
Thanks!
> Restore snapshot in parallel
> ----------------------------
>
> Key: HBASE-21394
> URL: https://issues.apache.org/jira/browse/HBASE-21394
> Project: HBase
> Issue Type: Improvement
> Reporter: Zheng Hu
> Assignee: Zheng Hu
> Priority: Major
> Fix For: 3.0.0, 2.2.0, 2.1.2
>
>
> Our MapReduce/Spark job is highly dependent on SnapshotScanner. When restore
> a big table for SnapshotScanner, it'll take hours ..
> Restore snapshot in parallel will helps a lot.
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