[jira] [Commented] (TEZ-4397) Open Tez Input splits asynchronously

["Syed Shameerur Rahman (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-4397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17682391#comment-17682391 ] 

Syed Shameerur Rahman commented on TEZ-4397:
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[~abstractdog] 
On debugging i found that This was due Hive’s operator initialization which are designed in a way that only one split can be opened at a time since they share the [IOContext|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/io/IOContext.java] variable so when multiple splits are opened at the same time the shared variable gets overwritten and doesn’t match the correct context.

I will take this up separately in Hive, But for Tez I have created a new PR with the following changes
1. Disable the feature by default (no. of reader = 1)

> Open Tez Input splits asynchronously
> ------------------------------------
>
>                 Key: TEZ-4397
>                 URL: https://issues.apache.org/jira/browse/TEZ-4397
>             Project: Apache Tez
>          Issue Type: Task
>            Reporter: Ramesh Kumar Thangarajan
>            Assignee: Ramesh Kumar Thangarajan
>            Priority: Major
>          Time Spent: 2h 40m
>  Remaining Estimate: 0h
>
> Tez input splits can be opened asynchronously. This will reduce the amount of time spent for s3 to prepare the connection and opening the object.



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