[jira] [Commented] (KAFKA-9450) Decouple inner state flushing from committing

["Navinder Brar (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-9450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17036093#comment-17036093 ] 

Navinder Brar commented on KAFKA-9450:
--------------------------------------

Sure, [~ableegoldman]. I will create a ticket. Checked with Rocksdb, they will not cherry-pick to 5.x version. So, we will have to wait I guess.

> Decouple inner state flushing from committing
> ---------------------------------------------
>
>                 Key: KAFKA-9450
>                 URL: https://issues.apache.org/jira/browse/KAFKA-9450
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>            Reporter: Sophie Blee-Goldman
>            Priority: Major
>
> When EOS is turned on, the commit interval is set quite low (100ms) and all the store layers are flushed during a commit. This is necessary for forwarding records in the cache to the changelog, but unfortunately also forces rocksdb to flush the current memtable before it's full. The result is a large number of small writes to disk, losing the benefits of batching, and a large number of very small L0 files that are likely to slow compaction.
> Since we have to delete the stores to recreate from scratch anyways during an unclean shutdown with EOS, we may as well skip flushing the innermost StateStore during a commit and only do so during a graceful shutdown, before a rebalance, etc. This is currently blocked on a refactoring of the state store layers to allow decoupling the flush of the caching layer from the actual state store.
> Note that this is especially problematic with EOS due to the necessarily-low commit interval, but still hurts even with at-least-once and a much larger commit interval. 



--
This message was sent by Atlassian Jira
(v8.3.4#803005)