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https://issues.apache.org/jira/browse/CASSANDRA-5661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13693876#comment-13693876
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Jeremiah Jordan commented on CASSANDRA-5661:
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[~xedin] LCS == LeveledCompactionStrategy. While in theory I like the idea of
the searchers in most cases expiring quicker with timers, in practice since
these are on the heap, and LCS defaults to only 5 MB files per levels, you can
have A LOT of sstables, 200 per GB... Which as [~jbellis] mentioned makes # of
sstables * concurrent readers a big problem, which was the problem hit above.
So we really need to bound memory usage with a hard cap, not the fuzzy cap of
"how many can I open in X seconds".
1k reqs/sec hitting a 4 level deep LCS CF could mean 4k Reader's (~500 MB)
created per second. Now that I say that out loud, I almost think we should go
back to not caching these at all so they always just get recycled in young gen
and never have a chance to hit old gen. I guess it could be a config parameter
which defaults on for STCS and off for LCS. Since STCS work loads have no
where near as many sstables.
> Discard pooled readers for cold data
> ------------------------------------
>
> Key: CASSANDRA-5661
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5661
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.2.1
> Reporter: Jonathan Ellis
> Assignee: Pavel Yaskevich
> Fix For: 1.2.7
>
>
> Reader pooling was introduced in CASSANDRA-4942 but pooled
> RandomAccessReaders are never cleaned up until the SSTableReader is closed.
> So memory use is "the worst case simultaneous RAR we had open for this file,
> forever."
> We should introduce a global limit on how much memory to use for RAR, and
> evict old ones.
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