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https://issues.apache.org/jira/browse/HADOOP-7614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13211093#comment-13211093
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Steve Loughran commented on HADOOP-7614:
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Configurations last a long time and can get passed around, so I'm reluctant do
anything that could leak things or even add XML files to the in-memory
configuration.
removing the behaviour altogether would break things (it's hard to tell from
the general Object interface)
I think in this situation, handling reloading by doing nothing may be the best
tactic; possibly warning the user somehow. Once an inputstream has been loaded,
the {{loadDefaults}} flag could be set to false. Yet that would change
behaviour in copied configurations, that will not crash on a reload.
> Reloading configuration when using imputstream resources results in
> org.xml.sax.SAXParseException
> -------------------------------------------------------------------------------------------------
>
> Key: HADOOP-7614
> URL: https://issues.apache.org/jira/browse/HADOOP-7614
> Project: Hadoop Common
> Issue Type: Bug
> Components: conf
> Affects Versions: 0.21.0
> Reporter: Ferdy Galema
> Priority: Minor
> Attachments: HADOOP-7614-v1.patch, HADOOP-7614-v2.patch
>
>
> When using an inputstream as a resource for configuration, reloading this
> configuration will throw the following exception:
> Exception in thread "main" java.lang.RuntimeException:
> org.xml.sax.SAXParseException: Premature end of file.
> at
> org.apache.hadoop.conf.Configuration.loadResource(Configuration.java:1576)
> at
> org.apache.hadoop.conf.Configuration.loadResources(Configuration.java:1445)
> at
> org.apache.hadoop.conf.Configuration.getProps(Configuration.java:1381)
> at org.apache.hadoop.conf.Configuration.get(Configuration.java:569)
> ...
> Caused by: org.xml.sax.SAXParseException: Premature end of file.
> at
> com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:249)
> at
> com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:284)
> at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:124)
> at
> org.apache.hadoop.conf.Configuration.loadResource(Configuration.java:1504)
> ... 4 more
> To reproduce see following testcode:
> Configuration conf = new Configuration();
> ByteArrayInputStream bais = new
> ByteArrayInputStream("<configuration></configuration>".getBytes());
> conf.addResource(bais);
> System.out.println(conf.get("blah"));
> conf.addResource("core-site.xml"); //just add a named resource, doesn't
> matter which one
> System.out.println(conf.get("blah"));
> Allowing inputstream resources is flexible, but in cases such as this in can
> lead to difficult to debug problems.
> What do you think is the best solution? We could:
> A) reset the inputstream after it is read instead of closing it (but what to
> do when the stream does not support marking?)
> B) leave it up to the client (for example make sure you implement close() so
> that it resets the steam)
> C) when reading the inputstream for the first time, cache or wrap the
> contents somehow so that is can be read multiple times (let's at least
> document it)
> D) remove inputstream method altogether
> e) something else?
> For now I have attached a patch for solution A.
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