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https://issues.apache.org/jira/browse/MAPREDUCE-4822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13572801#comment-13572801
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Jason Lowe commented on MAPREDUCE-4822:
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The intent of TaskAttemptID.forName() is to be the inverse of its toString().
In these cases we have a valid TaskAttemptID, so the IllegalArgumentException
should never be thrown in this context unless forName() or toString() is
broken. And I can't imagine why someone would expect and rely on that behavior
if it somehow were throwing it. We have an ID, someone is asking for it, why
convert it to a string and back before returning it?
To sum up, {{return TaskAttemptID.forName(taskAttempt.toString())}} should just
be {{return taskAttempt}}. If you're not comfortable making the change, that's
fine let me know. We can either file a followup JIRA or I can post the changes
to the patch.
> Unnecessary conversions in History Events
> -----------------------------------------
>
> Key: MAPREDUCE-4822
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4822
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: jobhistoryserver
> Affects Versions: 0.23.4
> Reporter: Robert Joseph Evans
> Assignee: Chu Tong
> Priority: Trivial
> Labels: patch
> Fix For: 0.24.0
>
> Attachments: MAPREDUCE-4822.patch
>
>
> There are a number of conversions in the Job History Event classes that are
> totally unnecessary. It appears that they were originally used to convert
> from the internal avro format, but now many of them do not pull the values
> from the avro they store them internally.
> For example:
> {code:title=TaskAttemptFinishedEvent.java}
> /** Get the task type */
> public TaskType getTaskType() {
> return TaskType.valueOf(taskType.toString());
> }
> {code}
> The code currently is taking an enum, converting it to a string and then
> asking the same enum to convert it back to an enum. If java work properly
> this should be a noop and a reference to the original taskType should be
> returned.
> There are several places that a string is having toString called on it, and
> since strings are immutable it returns a reference to itself.
> The various ids are not immutable and probably should not be changed at this
> point.
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