[jira] [Resolved] (CASSANDRA-5661) Discard pooled readers for cold data

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-5661?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis resolved CASSANDRA-5661.
---------------------------------------

       Resolution: Fixed
    Fix Version/s: 1.2.10

We're now well into 1.2's "stabilization" period, so even if Ben's multiway cache were available tomorrow I'd be uneasy about pushing it out to our "oldstable" branch.

So I've committed Pavel's original queue-based cache with light revisions (primarily adding a conf setting to allow overriding the size).

Longer term I think CASSANDRA-6045 may be a better approach overall.
                
> 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: 1.2.10, 2.0.1
>
>         Attachments: CASSANDRA-5661-global-multiway-cache.patch, CASSANDRA-5661.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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