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https://issues.apache.org/jira/browse/HUDI-4959?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ethan Guo updated HUDI-4959:
----------------------------
Fix Version/s: 0.12.2
(was: 0.13.0)
> Serializing objects using Kryo fails to deserialize data back w/o prior
> registration
> ------------------------------------------------------------------------------------
>
> Key: HUDI-4959
> URL: https://issues.apache.org/jira/browse/HUDI-4959
> Project: Apache Hudi
> Issue Type: Bug
> Components: writer-core
> Affects Versions: 0.12.0
> Reporter: Alexey Kudinkin
> Assignee: Alexey Kudinkin
> Priority: Blocker
> Labels: pull-request-available
> Fix For: 0.12.2
>
>
> Originally reported in:
> [https://github.com/apache/hudi/issues/6621]
>
> Kryo (used in SerializationUtils) by default allows class objects to be
> serialized w/o prior registration w/ Kryo: in that case Kryo will encode the
> first occurrence of the object of a particular class with full class-name,
> but subsequent occurrences will be using class-id associated with it (on the
> fly).
> This poses issues for durable serialization (when we persist such serialized
> layout) in this case we're trying to deserialize file that doesn't have the
> class-name encoded and since user is running a different Spark job to read
> there's no association preserved in-memory either.
> *NOTE: We should be using custom serialization sequences for every object we
> serialize for durable persistence, and avoid using frameworks like Kryo for
> that.*
>
> ----
> *EDIT*
> I'm taking back my hypothesis that the issue is in the class encoding, after
> writing a small test to validate the issue i confirmed that Kryo actually
> writes out full class-name for all classes registered implicitly (as it
> should).
> It seems that the problem is actually indeed in misalignment of the Avro
> versions as reported by [@KnightChess|https://github.com/KnightChess]:
> quick-checking i see that b/w Avro 1.8.2 and 1.10.2, {{Utf8}} actually had
> one more field added:
> {code:java}
> // 1.8.2
> private byte[] bytes = EMPTY;
> private int length;
> private String string;
> // 1.10.2
> private byte[] bytes;
> private int hash;
> private int length;
> private String string; {code}
>
> {{ }}Provided that we're relying on Kryo to generate serializer for
> {{orderingVal}} that could be {{Utf8}} (based on {{{}FieldSerializer{}}}) it
> would actually explain why it couldn't deserialize it back (since they will
> have different serializers).
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