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https://issues.apache.org/jira/browse/BOOKKEEPER-447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13509293#comment-13509293
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Flavio Junqueira commented on BOOKKEEPER-447:
---------------------------------------------
I have a few comments and questions here:
* I'm not sure what this is doing:
{code}
+ cleanPages.tryAcquire(100, TimeUnit.MILLISECONDS);
{code}
if the 100 ms elapses and there has been no release, then it means that there
is no clean page, no?
* Should we rename BookieTest to something less general, like
BookieLedgerIndexTest?
* Check the javadoc for testIndexPageEviction(), it has typos.
* There is this comment in this same test:
{noformat}
// don't start the bookie, this way sync thread wont run
{noformat}
but the code does start the bookie right after. Is this correct? Is it
referring to second occurrence of "new Bookie"?
> 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: Ivan Kelly
> Labels: patch
> Fix For: 4.2.0, 4.1.1
>
> Attachments:
> 0001-BOOKKEEPER-447-LedgerCacheImpl-waits-on-semaphore-no.patch,
> BOOKKEEPER-447.diff, perf.png
>
>
> 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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