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https://issues.apache.org/jira/browse/HBASE-19468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16285831#comment-16285831
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Anoop Sam John commented on HBASE-19468:
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I see after every flush we add the flushed file name into flushedStoreFiles.
Need not be there any parallel read ops happening at all.. Still we keep on
adding. Unless there is calls to next/seek/reseek by scanners, there is no
possible removal from this flushedStoreFiles List. So this list size will keep
on growing when it is a write only load? Missing some thing?
> FNFE during scans and flushes
> -----------------------------
>
> Key: HBASE-19468
> URL: https://issues.apache.org/jira/browse/HBASE-19468
> Project: HBase
> Issue Type: Sub-task
> Components: regionserver, Scanners
> Affects Versions: 1.3.1
> Reporter: Thiruvel Thirumoolan
> Priority: Critical
> Fix For: 2.0.0, 1.4.1, 1.5.0, 1.3.3
>
>
> We see FNFE exceptions on our 1.3 clusters when scans and flushes happen at
> the same time. This causes regionserver to throw a UnknownScannerException
> and client retries.
> This happens during the following sequence:
> 1. Scanner open, client fetched some rows from regionserver and working on it
> 2. Flush happens and storeScanner is updated with flushed files
> (StoreScanner.updateReaders())
> 3. Compaction discharger runs and cleans up the newly flushed file as we
> don't have new scanners on it yet.
> 4. Client issues scan.next and during StoreScanner.resetScannerStack(), we
> get a FNFE. RegionServer throws a UnknownScannerThe client retries in 1.3.
> With branch-1.4, the scan fails with a DoNotRetryIOException.
> [~ram_krish], My proposal is to increment the reader count during
> updateReaders() and decrement it during resetScannerStack(), so discharger
> doesn't clean it up. Scan lease expiries also have to be taken care of. Am I
> missing anything? Is there a better approach?
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