[jira] [Commented] (CASSANDRA-8833) Stop opening compaction results early

["Marcus Eriksson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-8833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14352719#comment-14352719 ] 

Marcus Eriksson commented on CASSANDRA-8833:
--------------------------------------------

Coming back to this, what I would like is:

# run benchmarks again, this time on ssds ([~enigmacurry] could your team help out with that?)
# see if we can solve the index summary redistribution some other way (only do it on compaction?) to be able to make SSTableReader totally immutable again, got any insight here [~thobbs]?

> Stop opening compaction results early
> -------------------------------------
>
>                 Key: CASSANDRA-8833
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8833
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Marcus Eriksson
>             Fix For: 2.1.4
>
>
> We should simplify the code base by not doing early opening of compaction results. It makes it very hard to reason about sstable life cycles since they can be in many different states, "opened early", "starts moved", "shadowed", "final", instead of as before, basically just one (tmp files are not really 'live' yet so I don't count those). The ref counting of shared resources between sstables in these different states is also hard to reason about. This has caused quite a few issues since we released 2.1
> I think it all boils down to a performance vs code complexity issue, is opening compaction results early really 'worth it' wrt the performance gain? The results in CASSANDRA-6916 sure look like the benefits are big enough, but the difference should not be as big for people on SSDs (which most people who care about latencies are)
> WDYT [~benedict] [~jbellis] [~iamaleksey] [~JoshuaMcKenzie]?



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