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https://issues.apache.org/jira/browse/BOOKKEEPER-336?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13411389#comment-13411389
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Sijie Guo commented on BOOKKEEPER-336:
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{quote}
With a short timeout, we will possibly have a lot of false positives because a
request may have been caused by a transient problem. False positives make
maintaining the blacklist difficult.
{quote}
short timeout provided the mechanism to quick switch to try next bookie. but it
doesn't change read sequence, next read still started from same slow bookie.
same long latency needs for following read requests.
re-ordering the read sequence could avoid it. I treated blacklist as a kind of
mechanism to achieve re-ordering. I think both needs for read latency.
> bookie readEntries is taking more time if the ensemble has failed bookie(s)
> ---------------------------------------------------------------------------
>
> Key: BOOKKEEPER-336
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-336
> Project: Bookkeeper
> Issue Type: Bug
> Affects Versions: 4.1.0
> Reporter: Brahma Reddy Battula
> Assignee: Rakesh R
> Attachments: BOOKKEEPER-336.patch
>
>
> Scenario:
> 1) Start three bookies. Create ledger with ensemblesize=3, quorumsize=2
> 2) Add 100 entries to this ledger
> 3) Make first bookie down and read the entries from 0-99
> Output: Each entry is going to fetch from the failed bookie and is waiting
> for the bookie connection timeout, only after failure going to next bookie.
> This is affecting the read entry performance.
> Impact: Namenode switching time will be affected by adding this failed bookie
> readTimeOut also.
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