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https://issues.apache.org/jira/browse/HADOOP-19641?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anuj Modi reassigned HADOOP-19641:
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    Assignee: Manika Joshi  (was: Anuj Modi)

> ABFS: [ReadAheadV2] First Read should bypass ReadBufferManager
> --------------------------------------------------------------
>
>                 Key: HADOOP-19641
>                 URL: https://issues.apache.org/jira/browse/HADOOP-19641
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/azure
>    Affects Versions: 3.4.1
>            Reporter: Anuj Modi
>            Assignee: Manika Joshi
>            Priority: Major
>              Labels: Performance
>
> We have observed this across multiple workload runs that when we start 
> reading data from input stream. The first read which came to input stream has 
> to be read synchronously even if we trigger prefetch request for that 
> particular offset. Most of the times we end up doing extra work of checking 
> if the prefetch is trigerred, removing prefetch from the pending queue and go 
> ahead to do a direct remote read in workload thread itself.
> To avoid all this overhead, we will always bypass read ahead for the very 
> first read of each input stream and trigger read aheads for second read 
> onwards.



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