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https://issues.apache.org/jira/browse/HADOOP-11223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14292586#comment-14292586
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Varun Saxena commented on HADOOP-11223:
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Thanks [~cmccabe] and [~gopalv] for your comments.
>From the preceding discussion it seemed immutability was not to be considered.
>And programmers using the class will take care of it.
Can't we keep a simple flag in Configuration class to make it read only.
DefaultConfiguration can probably extend Configuration. We can make this flag
to be set only from DefaultConfiguration(in constructor) and disallow any
operations which involve setting keys or loading resources, if this flag is set.
> 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: Varun Saxena
> Labels: Performance
> Attachments: HADOOP-11223.001.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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