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https://issues.apache.org/jira/browse/BOOKKEEPER-447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13487381#comment-13487381
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Sijie Guo commented on BOOKKEEPER-447:
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{quote}
The recent journal is not flushed to begin with, they cannot possibly be
replayed.
{quote}
OK. I got the issue. Thanks [[email protected]] for clarification.
{quote}
If you agree, then what if we simply flush the entry log before we flush the
ledger cache in InterleavedLedgerStorage flush?
{quote}
[~fpj] I think the problem here is ledger storage flushed before journal
flushed. Although it could avoid IOException reading ledger index as your
proposal to change the flush order in ledger storage, it volatiles the contract
for a bookie server, who ack an entry after the entry has been committed to
journal. I would prefer Robin's proposal.
> Bookie can fail to recover if index pages flushed before ledger flush
> acknowledged
> ----------------------------------------------------------------------------------
>
> Key: BOOKKEEPER-447
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-447
> Project: Bookkeeper
> Issue Type: Bug
> Components: bookkeeper-server
> Affects Versions: 4.2.0
> Reporter: Yixue (Andrew) Zhu
> Assignee: Robin Dhamankar
> Labels: patch
> Fix For: 4.2.0
>
>
> Bookie index page steal (LedgerCacheImpl::grabCleanPage) can cause index file
> to reflect unacknowledged entries (due to flushLedger). Suppose ledger and
> entry fail to flush due to Bookkeeper server crash, it will cause ledger
> recovery not able to use the bookie afterward, due to
> InterleavedStorageLedger::getEntry throws IOException.
> If the ackSet bookies all experience this problem (DC environment), the
> ledger will not be able to recover.
> The problem here essentially a violation of WAL. One reasonable fix is to
> track ledger flush progress (either per-ledger entry, or per-topic message).
> Do not flush index pages which tracks entries whose ledger (log) has not been
> flushed.
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