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https://issues.apache.org/jira/browse/HADOOP-18106?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mukund Thakur updated HADOOP-18106:
-----------------------------------
    Fix Version/s: 3.3.5

> Handle memory fragmentation in S3 Vectored IO implementation.
> -------------------------------------------------------------
>
>                 Key: HADOOP-18106
>                 URL: https://issues.apache.org/jira/browse/HADOOP-18106
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>            Reporter: Mukund Thakur
>            Assignee: Mukund Thakur
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 3.3.5
>
>          Time Spent: 4.5h
>  Remaining Estimate: 0h
>
> As we have implemented merging of ranges in the S3AInputStream implementation 
> of vectored IO api, it can lead to memory fragmentation. Let me explain by 
> example.
>  
> Suppose client requests for 3 ranges. 
> 0-500, 700-1000 and 1200-1500.
> Now because of merging, all the above ranges will get merged into one and we 
> will allocate a big byte buffer of 0-1500 size but return sliced byte buffers 
> for the desired ranges.
> Now once the client is done reading all the ranges, it will only be able to 
> free the memory for requested ranges and memory of the gaps will never be 
> released for eg here (500-700 and 1000-1200).
>  



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