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https://issues.apache.org/jira/browse/HBASE-7671?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13568591#comment-13568591
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chunhui shen commented on HBASE-7671:
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bq.Did you consider preventing flushes if server is in abort state?
There's a theoretical possibility that flush again between last failure and
setting server stopped.(Aborting server is called by the flush caller)
But I think we could take this simpler fix.
Does the write lock prevent a flush happening while copying kvs to the existing
snapshot?
Yes, at the same time, there will be only one flush for the same region. It is
guaranteed by the WriteState of region.
> Flushing memstore again after last failure could cause data loss
> ----------------------------------------------------------------
>
> Key: HBASE-7671
> URL: https://issues.apache.org/jira/browse/HBASE-7671
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.94.4
> Reporter: chunhui shen
> Assignee: chunhui shen
> Priority: Critical
> Fix For: 0.96.0, 0.94.6
>
> Attachments: HBASE-7671.patch, HBASE-7671v2.patch, HBASE-7671v3.patch
>
>
> See the following logs first:
> {code}
> 2013-01-23 18:58:38,801 INFO org.apache.hadoop.hbase.regionserver.Store:
> Flushed , sequenceid=9746535080, memsize=101.8m, into tmp file
> hdfs://dw77.kgb.sqa.cm4:9900/hbase-test3/writetest1/8dc14e35b4d7c0e481e0bb30849cff7d/.tmp/bebeeecc56364b6c8126cf1dc6782a25
> 2013-01-23 18:58:41,982 WARN org.apache.hadoop.hbase.regionserver.MemStore:
> Snapshot called again without clearing previous. Doing nothing. Another
> ongoing flush or did we fail last attempt?
> 2013-01-23 18:58:43,274 INFO org.apache.hadoop.hbase.regionserver.Store:
> Flushed , sequenceid=9746599334, memsize=101.8m, into tmp file
> hdfs://dw77.kgb.sqa.cm4:9900/hbase-test3/writetest1/8dc14e35b4d7c0e481e0bb30849cff7d/.tmp/4eede32dc469480bb3d469aaff332313
> {code}
> The first time memstore flush is failed when commitFile()(Logged the first
> edit above), then trigger server abort, but another flush is coming
> immediately(could caused by move/split,Logged the third edit above) and
> successful.
> For the same memstore's snapshot, we get different sequenceid, it causes data
> loss when replaying log edits
> See details from the unit test case in the patch
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