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From "Stu Hood (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Edited] (CASSANDRA-3162) use weak references to SlabAllocator regions
Date Thu, 08 Sep 2011 18:24:08 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13100533#comment-13100533
] 

Stu Hood edited comment on CASSANDRA-3162 at 9/8/11 6:22 PM:
-------------------------------------------------------------

I'm not sure I like using this many WeakReferences in the common case: couldn't we get approximately
the same effect by just nulling the 'data' field of the Region immediately after it has been
retired? Then the filledRegions list would be an empty shell of regions.

      was (Author: stuhood):
    I'm not sure I like using this many WeakReferences in the common case: couldn't we get
approximately the same effect by just nulling the 'data' field of the Region immediately after
it has been retired? Then the filledRegions list would be an empty shell of references.
  
> 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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