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https://issues.apache.org/jira/browse/BOOKKEEPER-336?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13527900#comment-13527900
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Flavio Junqueira commented on BOOKKEEPER-336:
---------------------------------------------
Overall it looks pretty good. I have a number of comments, not necessarily
blockers for this patch:
# In the case the digest of an entry doesn't match, we will discard the entry,
although we have heard from the bookie. Consequently, we need to request
another entry, and possibly this is handled through a different code path. Is
it the case? In the case there is a different code path to deal with invalid
entries, we may want to consider coalescing them as much as possible.
# It would be great to add documentation for the new parameter and to update
conf/bk_server.conf
# The default value for the speculative read seems a large. Is there any reason
why we shouldn't be a bit more aggressive with the default value, especially
because we can turn off speculative reads altogether?
# Please fix typos in the comments. I've seen at least a couple, like
"functionallity".
# In the future, it might be a good idea to use failure detection techniques
like phi accrual for the speculative read timeout instead of having a fixed
value.
> 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: Ivan Kelly
> Fix For: 4.2.0
>
> Attachments:
> 0001-BOOKKEEPER-336-bookie-readEntries-is-taking-more-tim.patch,
> 0001-BOOKKEEPER-336-bookie-readEntries-is-taking-more-tim.patch,
> 0002-BOOKKEEPER-336-bookie-readEntries-is-taking-more-tim.patch,
> 0002-BOOKKEEPER-336-bookie-readEntries-is-taking-more-tim.patch,
> 0002-BOOKKEEPER-336-bookie-readEntries-is-taking-more-tim.patch,
> BOOKKEEPER-336.1.patch, BOOKKEEPER-336.draft1.diff, 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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