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https://issues.apache.org/jira/browse/CASSANDRA-20085?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jon Haddad reassigned CASSANDRA-20085:
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    Assignee: Jon Haddad

> Move CompactionAwareWriter.append to separate thread
> ----------------------------------------------------
>
>                 Key: CASSANDRA-20085
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-20085
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jon Haddad
>            Assignee: Jon Haddad
>            Priority: Normal
>         Attachments: image-2024-11-15-09-45-51-450.png, 
> image-2024-11-15-09-50-41-854.png
>
>
> I'm examining a 5.0 cluster, mostly default settings except these overrides:
> {noformat}
> cluster_name: "density"
> num_tokens: 4
> concurrent_reads: 64
> concurrent_writes: 64
> trickle_fsync: true
> endpoint_snitch: "Ec2Snitch"
> compaction_throughput: 0MiB/s
> key_cache_migrate_during_compaction: false
> {noformat}
> Here's a flame graph of compaction taken with these settings:
> {noformat}
> asprof -e wall -X '*Unsafe.park*' -X '*Native.epollWait' -I '*compaction*' 
> {noformat}
> [^image-2024-11-15-09-50-41-854.png]
> and in reverse:
> [^image-2024-11-15-09-45-51-450.png]
> It's clear we can get an easy win by moving the writing portion of compaction 
> to a dedicated thread (ExecutorService.newSingleThreadExecutor() ?), instead 
> of blocking in the same one. For this use case, it would improve compaction 
> throughput by about 2x.



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