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https://issues.apache.org/jira/browse/HADOOP-11223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16769789#comment-16769789
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Michael Miller commented on HADOOP-11223:
-----------------------------------------
{quote}the "Unmodifiable" one is not immutable (see earlier discussion about
addDefaultResource).
{quote}
Correct. I understand a true immutable object is not possible because of the
static methods. This is why we would settle for an "Unmodifiable" object. This
would at least prevent changes on the object itself, for example, in our
Testing framework:
{code:java}
public void test(ServerContext context) {
Configuration conf = context.getHadoopConf();
conf.set("prop", "value");
}
{code}
Here we would prefer an error be thrown since the framework expects
configuration to be set a certain way. It is a lot easier to make this mistake
then to think "I want to change a property so I am going to create another
configuration, call this static method and reload it ".
> 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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