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From "Amir Langer (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-6659) Create a Block List
Date Thu, 10 Jul 2014 11:20:06 GMT
Amir Langer created HDFS-6659:

             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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