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https://issues.apache.org/jira/browse/HADOOP-1197?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12486455
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Andrzej Bialecki commented on HADOOP-1197:
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These methods were added to support caching of transient Objects created within
the scope of a single task - especially Objects that are costly to instantiate,
and which follow a "singleton" pattern within the scope of the current task.
Examples: plugin registry, which requires reading and parsing a lot of config
files; individual plugin instances; processing chains composed of several
plugins, etc.
These Objects are not Writable, nor does it make sense to make them Writable -
the only purpose of this pattern is to avoid repetitive instantiation of
Configurable objects with the same Configuration instance.
If we remove this functionality from Hadoop, then a dozen Nutch subsystems
would break, since they rely on this feature. Nutch could implement its own
object cache, but then a lot of APIs would have to be changed to take not only
a Configuration instance but also an object cache singleton ..
Perhaps a clarification in the javadoc would be sufficient?
> The misleading Configuration.set(String, Object) should be removed
> ------------------------------------------------------------------
>
> Key: HADOOP-1197
> URL: https://issues.apache.org/jira/browse/HADOOP-1197
> Project: Hadoop
> Issue Type: Bug
> Components: conf
> Affects Versions: 0.12.2
> Reporter: Owen O'Malley
> Assigned To: Owen O'Malley
> Priority: Minor
> Fix For: 0.13.0
>
>
> I think that the confusing methods in Configuration:
> set(String, Object)
> getObject(String)
> get(String, Object)
> should be deprecated. Users expect them to work and in a distributed
> environment, there is almost no way to make them work correctly. If some user
> really needs the functionality, we should implement it right and require that
> the objects be Writable and serialize them into the Configuration.
> Thoughts?
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