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https://issues.apache.org/jira/browse/FLINK-16385?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17321407#comment-17321407
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Flink Jira Bot commented on FLINK-16385:
----------------------------------------
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-16385
> URL: https://issues.apache.org/jira/browse/FLINK-16385
> Project: Flink
> Issue Type: Test
> Components: Table SQL / Runtime
> Reporter: cpugputpu
> Priority: Minor
> Labels: stale-minor
>
> The tests 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.
> [ERROR]
> testStringToMap(org.apache.flink.table.planner.expressions.ScalarFunctionsTest)
> org.junit.ComparisonFailure: Wrong result for: [STR_TO_MAP(f46)] optimized
> to: [STR_TO_MAP($46)]
> expected:<\{test1=1, test2=2, test3=3}> but was:<\{test2=2, test1=1, test3=3}>
>
> The root cause of this failure lies in a HashMap initialized in
> _flink-table/flink-table-runtime-blink/src/main/java/org/apache/flink/table/runtime/functions/SqlFunctionUtils.java_
> and a brief stack trace of the HashMap's iterator is presented for your
> reference:
> _java.util.HashMap$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 the failure any more and the code will be more stable,
> free of this non-deterministic behaviour.
>
>
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