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https://issues.apache.org/jira/browse/BOOKKEEPER-564?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13623832#comment-13623832
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Sijie Guo commented on BOOKKEEPER-564:
--------------------------------------
the jira is to separate checkpoint with flush, a checkpoint just need to sync
old data before checkpoint without affecting current written data. in your
patch, each time you synced data, you still flush everything dirty in ledger
storage which affects under writing operations. the point why we trigger
checkpoint when rolling the data is new data will be added to a new entry
logger (which is in filesystem page cache) when old data is syncing to disk. so
adding operation will not be affected by background syncing.
And this is also important when adapting skiplist proposal. if you triggered
checkpoint in sync thread, you might end up flushing current in-use skiplist,
which is bad.
BTW, checkpoint here doesn't resolve BOOKKEEPER-572 directly, but it provides
clear interface for checkpoints. BOOKKEEPER-572 could use its interface, this
is the point why I mentioned this jira in BOOKKEEPER-572.
> Better checkpoint mechanism
> ---------------------------
>
> Key: BOOKKEEPER-564
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-564
> Project: Bookkeeper
> Issue Type: Improvement
> Components: bookkeeper-server
> Reporter: Sijie Guo
> Assignee: Sijie Guo
> Fix For: 4.3.0
>
> Attachments: 0002-BOOKKEEPER-564-Better-checkpoint-mechanism.patch,
> BOOKKEEPER-564.patch
>
>
> Currently, SyncThread made a checkpoint too frequently, which affects
> performance. data is writing to entry logger file might be blocked by syncing
> same entry logger file, which affect bookie to achieve higher throughput. We
> could schedule checkpoint only when rotating an entry log file. so new
> incoming entries would be written to newer entry log file and old entry log
> file could be synced.
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