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https://issues.apache.org/jira/browse/BOOKKEEPER-458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13530395#comment-13530395
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Flavio Junqueira commented on BOOKKEEPER-458:
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The poll call has a timeout value, so if it times out, the call will return
null, no? Will the test throw an NPE instead?
> Annoy BKReadException error when changing ledger.
> -------------------------------------------------
>
> Key: BOOKKEEPER-458
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-458
> Project: Bookkeeper
> Issue Type: Bug
> Components: hedwig-server
> Reporter: Sijie Guo
> Assignee: Jiannan Wang
> Priority: Minor
> Fix For: 4.2.0
>
> Attachments: BOOKKEEPER-458.diff, BOOKKEEPER-458.diff
>
>
> Some annoy BKReadException are found when changing ledger.
> 1) suppose Topic T has ledger L1, storing messages starting from 1 - 100.
> 2) T changed ledger to write entry to ledger L2.
> 3) Before the entry is added successfully, Subscribe s subscribed topic T.
> ReadAhead cache tried to schedule a ReadAhead request to scan (103, 104).
> 4) RangeScanOp in BookKeeperPersistentManager executed to read entry 2 & 3
> from L2. but actually there was no entries in L2.
> {code:title=BookKeeperPersistentManager.java}
> // None of the old ledgers have this seq-id, we must use the
> // current ledger
> long endSeqId =
> topicInfo.currentLedgerRange.getStartSeqIdIncluded()
> + topicInfo.lastEntryIdAckedInCurrentLedger;
> if (endSeqId < startSeqId) {
> request.getCallback().scanFinished(request.ctx,
> ReasonForFinish.NO_MORE_MESSAGES); return;
> }
> {code}
> The code in BookKeeperPersistentManager is supposed to not scan any messages
> whose seq id is larger than lastEntryIdAckedInCurrentLedger. But
> lastEntryIdAckedInCurrentLedger isn't reset when changing ledger. so when
> RangeScanOp is executed, last entry id acked in previous ledger was used
> which causing calculating an error seq id for the boundary checking in
> RangeScanOp.
> The fix would be quite easy to reset lastEntryIdAckedInCurrentLedger when
> changing ledger. But we need a test case to cover this case.
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