[jira] [Updated] (CASSANDRA-3162) use weak references to SlabAllocator regions

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

     [ https://issues.apache.org/jira/browse/CASSANDRA-3162?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis updated CASSANDRA-3162:
--------------------------------------

    Attachment: 3162.txt

Patch to use a set built on MapMaker.weakKeys.

Also reduces region size to 1MB to make the overhead lower for the "lots of small CFs" use case.

> use weak references to SlabAllocator regions
> --------------------------------------------
>
>                 Key: CASSANDRA-3162
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3162
>             Project: Cassandra
>          Issue Type: Improvement
>    Affects Versions: 1.0
>            Reporter: Jonathan Ellis
>            Assignee: Jonathan Ellis
>            Priority: Minor
>             Fix For: 1.0
>
>         Attachments: 3162.txt
>
>
> Yang points out on CASSANDRA-2252,
> "Conceivably, one region would contain bytebuffer values of similar age. as more updates come in, all the columns in older regions are likely to have all died out, thus allowing us to free the entire region before flushing happens."
> So it's a bit of a corner case optimization, but easy to do and safe.

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