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https://issues.apache.org/jira/browse/FLINK-5874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15903624#comment-15903624
]
ASF GitHub Bot commented on FLINK-5874:
---------------------------------------
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/3501#discussion_r105239687
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/datastream/KeyedStream.java
---
@@ -114,9 +121,53 @@ public KeyedStream(DataStream<T> dataStream,
KeySelector<T, KEY> keySelector, Ty
dataStream.getTransformation(),
new KeyGroupStreamPartitioner<>(keySelector,
StreamGraphGenerator.DEFAULT_LOWER_BOUND_MAX_PARALLELISM)));
this.keySelector = keySelector;
- this.keyType = keyType;
+ this.keyType = validateKeyType(keyType);
}
-
+
+ private TypeInformation<KEY> validateKeyType(TypeInformation<KEY>
keyType) {
+ Stack<TypeInformation<?>> stack = new Stack<>();
+ stack.push(keyType);
+
+ while (!stack.isEmpty()) {
+ TypeInformation<?> typeInfo = stack.pop();
+
+ if (!validateKeyTypeIsHashable(typeInfo)) {
+ throw new InvalidProgramException("This type ("
+ keyType + ") cannot be used as key.");
--- End diff --
Let's include ```typeInfo``` in this exception as well to narrow it down
for the user. We may even want to delay the exception until we scanned the
entire type and report all invalid keys at once.
> Reject arrays as keys in DataStream API to avoid inconsistent hashing
> ---------------------------------------------------------------------
>
> Key: FLINK-5874
> URL: https://issues.apache.org/jira/browse/FLINK-5874
> Project: Flink
> Issue Type: Bug
> Components: DataStream API
> Affects Versions: 1.2.0, 1.1.4
> Reporter: Robert Metzger
> Assignee: Kostas Kloudas
> Priority: Blocker
>
> This issue has been reported on the mailing list twice:
> -
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Previously-working-job-fails-on-Flink-1-2-0-td11741.html
> -
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Arrays-values-in-keyBy-td7530.html
> The problem is the following: We are using just Key[].hashCode() to compute
> the hash when shuffling data. Java's default hashCode() implementation
> doesn't take the arrays contents into account, but the memory address.
> This leads to different hash code on the sender and receiver side.
> In Flink 1.1 this means that the data is shuffled randomly and not keyed, and
> in Flink 1.2 the keygroups code detect a violation of the hashing.
> The proper fix of the problem would be to rely on Flink's {{TypeComparator}}
> class, which has a type-specific hashing function. But introducing this
> change would break compatibility with existing code.
> I'll file a JIRA for the 2.0 changes for that fix.
> For 1.2.1 and 1.3.0 we should at least reject arrays as keys.
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