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https://issues.apache.org/jira/browse/FLINK-8836?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16383734#comment-16383734
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Stephan Ewen commented on FLINK-8836:
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I see. We can check what Kryo's philosophy on serializers is, but I would
assume that they should be stateless. It seems quite exotic to make those
stateful.
Personally, I cannot recall a case when there ever was a stateful Kryo
serializer. We could clearly document and require that in user-defined Kryo
serializers.
Going to the point that we pro-actively serialization-copy all user-defined
serializers is possible as well, as a hard last resort. We could do that for
all serializers that have fields and are passed not as classes, but objects.
> Duplicating a KryoSerializer does not duplicate registered default serializers
> ------------------------------------------------------------------------------
>
> Key: FLINK-8836
> URL: https://issues.apache.org/jira/browse/FLINK-8836
> Project: Flink
> Issue Type: Bug
> Components: Type Serialization System
> Reporter: Tzu-Li (Gordon) Tai
> Priority: Critical
>
> The {{duplicate()}} method of the {{KryoSerializer}} is as following:
> {code:java}
> public KryoSerializer<T> duplicate() {
> return new KryoSerializer<>(this);
> }
> protected KryoSerializer(KryoSerializer<T> toCopy) {
> defaultSerializers = toCopy.defaultSerializers;
> defaultSerializerClasses = toCopy.defaultSerializerClasses;
> kryoRegistrations = toCopy.kryoRegistrations;
> ...
> }
> {code}
> Shortly put, when duplicating a {{KryoSerializer}}, the
> {{defaultSerializers}} serializer instances are directly provided to the new
> {{KryoSerializer}} instance.
> This causes the fact that those default serializers are shared across two
> different {{KryoSerializer}} instances, and therefore not a correct duplicate.
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