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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-11223) Offer a read-only conf alternative to new Configuration()
Date Fri, 15 Feb 2019 21:14:00 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-11223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16769741#comment-16769741
] 

Gopal V commented on HADOOP-11223:
----------------------------------

bq. Mainly for performance and concurrency reasons we don't want the Hadoop Configuration
to change or be re-read.

This is not guaranteed by this patch, unfortunately - the "Unmodifiable" one is not immutable
(see earlier discussion about addDefaultResource).

> Offer a read-only conf alternative to new Configuration()
> ---------------------------------------------------------
>
>                 Key: HADOOP-11223
>                 URL: https://issues.apache.org/jira/browse/HADOOP-11223
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: conf
>            Reporter: Gopal V
>            Assignee: Michael Miller
>            Priority: Major
>              Labels: Performance
>         Attachments: HADOOP-11223.001.patch, HADOOP-11223.002.patch, HADOOP-11223.003.patch
>
>
> new Configuration() is called from several static blocks across Hadoop.
> This is incredibly inefficient, since each one of those involves primarily XML parsing
at a point where the JIT won't be triggered & interpreter mode is essentially forced on
the JVM.
> The alternate solution would be to offer a {{Configuration::getDefault()}} alternative
which disallows any modifications.
> At the very least, such a method would need to be called from 
> # org.apache.hadoop.io.nativeio.NativeIO::<clinit>()
> # org.apache.hadoop.security.SecurityUtil::<clinit>()
> # org.apache.hadoop.yarn.factory.providers.RecordFactoryProvider::<clinit>



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