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https://issues.apache.org/jira/browse/MAPREDUCE-5530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13778489#comment-13778489
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Robert Kanter commented on MAPREDUCE-5530:
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I was talking to [~sandyr] offline and he had an idea:
{{mapred.lib.CombineFileInputFormat}} would override {{isSplitable(JobContext
context, Path file)}} to call {{isSplitable(FileSystem fs, Path file)}}. I
believe this handles all situations except the one where the subclass overrides
both versions of {{isSplitable}}, but that's not likely to be common,
especially because {{isSplitable(JobContext context, Path file)}} isn't in
branch-1 anyway.
I think this is the best compromise and will solve most of the possible issues
here. Though, it would look pretty ugly:
{code:java}
@Override
protected boolean isSplitable(JobContext context, Path file) {
try {
return isSplitable(FileSystem.get(context.getConfiguration()), file);
}
catch (IOException ioe) {
throw new RuntimeException(ioe);
}
}
{code}
What do you think?
> Binary and source incompatibility in mapred.lib.CombineFileInputFormat
> between branch-1 and branch-2
> ----------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5530
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5530
> Project: Hadoop Map/Reduce
> Issue Type: Sub-task
> Components: mrv1, mrv2
> Affects Versions: 2.1.1-beta
> Reporter: Robert Kanter
> Assignee: Robert Kanter
> Priority: Blocker
> Attachments: MAPREDUCE-5530.patch
>
>
> {{mapred.lib.CombineFileInputFormat}} in branch-1 has this method:
> {code:java}
> protected boolean isSplitable(FileSystem fs, Path file)
> {code}
> In branch-2, {{mapred.lib.CombineFileInputFormat}} is now a subclass of
> {{mapreduce.lib.input.CombineFileInputFormat}}, from which it inherits the
> similar method:
> {code:java}
> protected boolean isSplitable(JobContext context, Path file)
> {code}
> This means that any code that subclasses
> {{mapred.lib.CombineFileInputFormat}} and does not provide its own
> implementation of {{protected boolean isSplitable(FileSystem fs, Path file)}}
> will not be binary or source compatible if it tries to call {{isSplitable}}
> with a {{FileSystem}} argument anywhere (that is, if compiled against
> branch-1, it will throw a {{NoSuchMethodError}} if run against branch-2;
> also, it won't even compile against branch-2).
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