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https://issues.apache.org/jira/browse/CASSANDRA-5661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13707694#comment-13707694
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Pavel Yaskevich commented on CASSANDRA-5661:
--------------------------------------------
I understand what is ideal use-case for LTQ is, I wanted to try it out since it
was mentioned couple of times to have better results than CLQ under load.
I expected FileCacheService to be faster, I was just trying to check how much
latency it actually adds even on such synthetic scenario as stress with no
writes nor compaction. I strongly think (and I explained why multiple times)
that we can't allow any degradation more than 0.5 ms in percentile on such
critical path and why expiring items in bulk is okey for us since, in steady
state, eviction would be driven by compactions cleaning all of open file
descriptors per compacted sstable, where timed expiry would be very infrequent
as read pattern doesn't change frequently in production systems.
> 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: 2.0
>
> Attachments: CASSANDRA-5661-multiway-per-sstable.patch,
> CASSANDRA-5661.patch, CASSANDRA-5661-v2-global-multiway-per-sstable.patch,
> DominatorTree.png, Histogram.png
>
>
> 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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