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https://issues.apache.org/jira/browse/FLINK-16386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17321406#comment-17321406
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Flink Jira Bot commented on FLINK-16386:
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This issue and all of its Sub-Tasks have not been updated for 180 days. So, it
has been labeled "stale-minor". If you are still affected by this bug or are
still interested in this issue, please give an update and remove the label. In
7 days the issue will be closed automatically.
> Use LinkedHashMap in SqlFunctionUtils.java
> ------------------------------------------
>
> Key: FLINK-16386
> URL: https://issues.apache.org/jira/browse/FLINK-16386
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / Runtime
> Reporter: cpugputpu
> Priority: Minor
> Labels: pull-request-available, stale-minor
> Time Spent: 20m
> Remaining Estimate: 0h
>
> The test in
> _org.apache.flink.table.planner.expressions.ScalarFunctionsTest#testStringToMap_
> can fail due to a different iteration order of a HashMap. The failure is
> presented as follows.
> _org.junit.ComparisonFailure: Wrong result for: [STR_TO_MAP(f46)] optimized
> to:[STR_TO_MAP($46)]
> expected:<\{test1=1, test2=2, test3=3}> but was:<\{test2=2, test1=1,
> test3=3}>_
> The root cause of this issue lies in a HashMap initialized in
> SqlFunctionUtils.java, which makes no guarantee about the iteration order. A
> brief stack trace of the HashMap's iterator is presented here:
> _java.util.HashMap$EntrySet.iterator(HashMap.java:1014)
> org.apache.flink.table.dataformat.DataFormatConverters$MapConverter.toBinaryMap(DataFormatConverters.java:1174)
> org.apache.flink.table.dataformat.DataFormatConverters$MapConverter.toInternalImpl(DataFormatConverters.java:1157)
> org.apache.flink.table.dataformat.DataFormatConverters$MapConverter.toInternalImpl(DataFormatConverters.java:1114)
> org.apache.flink.table.dataformat.DataFormatConverters$DataFormatConverter.toInternal(DataFormatConverters.java:290)
> TestFunction$144.map(Unknown_ Source)
> org.apache.flink.table.planner.expressions.utils.ExpressionTestBase.evaluateExprs(ExpressionTestBase.scala:152)
> The specification about HashMap says that "this class makes no guarantees as
> to the order of the map; in particular, it does not guarantee that the order
> will remain constant over time". The documentation is here for your
> reference: [https://docs.oracle.com/javase/8/docs/api/java/util/HashMap.html]
> The fix is to use LinkedHashMap instead of HashMap. In this way, the test
> will not suffer from failure any more and the code will be more stable, free
> of this non-deterministic behaviour.
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