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Posted to hdfs-dev@hadoop.apache.org by "Amir Langer (JIRA)" <ji...@apache.org> on 2014/07/10 13:20:06 UTC

[jira] [Created] (HDFS-6659) Create a Block List

Amir Langer created HDFS-6659:
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             Summary: 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
             Fix For: 3.0.0, 2.5.0


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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