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https://issues.apache.org/jira/browse/HADOOP-18215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17688634#comment-17688634
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ASF GitHub Bot commented on HADOOP-18215:
-----------------------------------------
ayushtkn commented on code in PR #4215:
URL: https://github.com/apache/hadoop/pull/4215#discussion_r1106140456
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableName.java:
##########
@@ -92,7 +92,7 @@ public static synchronized Class<?> getClass(String name,
Configuration conf
) throws IOException {
Class<?> writableClass = NAME_TO_CLASS.get(name);
if (writableClass != null)
- return writableClass.asSubclass(Writable.class);
+ return writableClass;
Review Comment:
That is what we expect, nobody should be expecting an exception. But this
method used to throw an exception earlier and we should ensure unless it is a
bug in the code, or the last option we should let it stay as is. Such changes
looks safe on hadoop side, but when a downstream project tries to upgrade and
if it is using such methods, it creates issues and blocks the way for
them.(Have seen that in the past with Hive/Tez)
So, I would say if we can avoid changing the existing behaviour of a public
method, we should do as a best effort
> Enhance WritableName to be able to return aliases for classes that use
> serializers
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-18215
> URL: https://issues.apache.org/jira/browse/HADOOP-18215
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Bryan Beaudreault
> Assignee: Bryan Beaudreault
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> WritableName allows users shim in aliases for writables, in the case where a
> SequenceFile was written with a Writable class that has since been renamed or
> moved to another package. However, this requires that the aliased class
> extend Writable.
> Separately it's possible to configure jobs with keys and values which don't
> actually extend Writable. Instead they are meant to be
> serialized/deserialized using the serialization classes defined in
> {{io.serializations}} config.
> Unfortunately, the current implementation does not support these key/value
> classes. All we need to do to support this is remove the
> {{.asSubclass(Writable.class)}} as is already the case for the default.
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