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https://issues.apache.org/jira/browse/HBASE-5569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13228553#comment-13228553
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Lars Hofhansl commented on HBASE-5569:
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Are my assumptions about scanning wrong here?
The test works as follows:
A bunch of thread alternate putting a column on RowA and deleting that column
on RowB in a transaction (next time delete is on RowA and put on RowB).
The they each scan starting with RowA and then expect to always see exactly one
KV (either the column in RowA or the one in RowB).
So this relies on a scan providing an atomic view over the two rows (which is
think should work if both RowA and RowB are rolled forward with the same MVCC
writepoint).
> TestAtomicOperation.testMultiRowMutationMultiThreads fails occasionally
> -----------------------------------------------------------------------
>
> Key: HBASE-5569
> URL: https://issues.apache.org/jira/browse/HBASE-5569
> Project: HBase
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Priority: Minor
>
> What I pieced together so far is that it is the *scanning* side that has
> problems sometimes.
> Every time I see a assertion failure in the log I see this before:
> {quote}
> 2012-03-12 21:48:49,523 DEBUG [Thread-211] regionserver.StoreScanner(499):
> Storescanner.peek() is changed where before =
> rowB/colfamily11:qual1/75366/Put/vlen=6,and after =
> rowB/colfamily11:qual1/75203/DeleteColumn/vlen=0
> {quote}
> The order of if the Put and Delete is sometimes reversed.
> The test threads should always see exactly one KV, if the "before" was the
> Put the thread see 0 KVs, if the "before" was the Delete the threads see 2
> KVs.
> This debug message comes from StoreScanner to checkReseek. It seems we still
> some consistency issue with scanning sometimes :(
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