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https://issues.apache.org/jira/browse/HIVE-13894?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15310815#comment-15310815
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Siddharth Seth commented on HIVE-13894:
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bq. All issues we have seen with java8 are order issues on.q.out files only.
This is due to a change in the HashMap implementation that Java8 did. To fix
the problem, we had to use LinkedHashMap in some places, or just change the
order of the .q.out file (that seems easier). Even if we use LinkedHashMap, we
had to re-order the .q.out file.
bq. Also, in some cases, like when HashMap is used within external libs like
antrl, avro or json (as in this case) regenerating the golden files in the only
viable option (using LinkedHashMap is not an option as it means adding new code
& associated cost just to re-order the output from these external libs)
HashMap has never guaranteed a sort ordering - which is why it can change
between Java 7 and Java8. I will not be surprised if a JDK from some other
company (Java8) - will have a different sort ordering. A LinkedHashMap solves
the problem - but potentially introduces an unnecessary performance hit and as
Mohit pointed out, we cannot guarantee the output from external libs.
To me, the ideal fix would be to change the validation infrastructure to allow
a sort within a single line. Probably a large change, and can be taken up at a
later point. Changing the q file output works for now, at least for jenkins
runs - until the next java version.
> Fix more json related JDK8 test failures Part 2
> -----------------------------------------------
>
> Key: HIVE-13894
> URL: https://issues.apache.org/jira/browse/HIVE-13894
> Project: Hive
> Issue Type: Bug
> Reporter: Mohit Sabharwal
> Assignee: Mohit Sabharwal
> Attachments: HIVE-13894.patch
>
>
> After merge of java8 branch to master, some more json ordering related
> failures
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