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From "Pavel Yaskevich (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-5661) Discard pooled readers for cold data
Date Sat, 13 Jul 2013 07:31:51 GMT


Pavel Yaskevich commented on CASSANDRA-5661:

Thanks, it worked that time, I did a quick test on local machine with global cache backed
by MultiwayPool.

MultiwayPool average run: median 3.1, 95th 4.7, 99.9th 21.9
FileCacheService (+ LinkedTranferQueue) average run: median 2.4, 95th 3.0, 99.9th 17.1

It's the same setup that I used in my previous test with no writes and no compaction.

I will try to experiment with ArrayBlockingQueue as we know upper bound on concurrency and
update my FileCacheService patch with either of them (LTQ vs. ABQ) soon.
> Discard pooled readers for cold data
> ------------------------------------
>                 Key: CASSANDRA-5661
>                 URL:
>             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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