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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-8757) IndexSummaryBuilder should construct itself offheap, and share memory between the result of each build() invocation
Date Thu, 12 Feb 2015 17:22:11 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8757?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14318575#comment-14318575
] 

Benedict commented on CASSANDRA-8757:
-------------------------------------

Patch available [here|github.com/belliottsmith/cassandra/tree/8757-offheapsummarybuilder]

The approach is pretty straight forward in principle: we split the offheap memory for the
summary into two allocations, the summary offsets and the summary entries - the latter composed
of the key and its offset in the index file. The offsets index from zero now, instead of from
the end of the offsets themselves, and so to maintain compatibility we do not change the serialization
format, on read/write we simply subtract/add the necessary offset. This split permits us to
have a separate chunk of memory for each that we can append to in the writer, so that a prefix
of both can be used to open a summary before we've finished writing. This permits us to share
memory between all early instances of a table.

> IndexSummaryBuilder should construct itself offheap, and share memory between the result
of each build() invocation
> -------------------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-8757
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8757
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Benedict
>            Assignee: Benedict
>             Fix For: 2.1.4
>
>




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