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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6659) Create a Block List
Date Mon, 11 Aug 2014 15:18:14 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6659?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14092871#comment-14092871
] 

Daryn Sharp commented on HDFS-6659:
-----------------------------------

I'd suggest trying to create a subclass of {{ChunkedArrayList}} that implements the custom
hole tracking you need.

> Create a Block List
> -------------------
>
>                 Key: HDFS-6659
>                 URL: https://issues.apache.org/jira/browse/HDFS-6659
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: namenode
>    Affects Versions: 2.4.1
>            Reporter: Amir Langer
>            Assignee: Amir Langer
>         Attachments: 0001-BlockList-a-list-of-Blocks-that-saves-memory-by-mana.patch
>
>
> BlockList - An efficient array based list that can extend its capacity with two main
features:
> 1. Gaps (result of remove operations) are managed internally without the need for extra
memory - We create a linked list of gaps by using the array index as references + An int to
the head of the gaps list. In every insert operation, we first use any available gap before
extending the array.
> 2. Array extension is done by chaining different arrays, not by allocating a larger array
and copying all its data across. This is a lot less heavy in terms of latency for that particular
call. It also avoids having large amount of contiguous heap space and so behaves nicer with
garbage collection.
>  



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