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https://issues.apache.org/jira/browse/FLINK-13910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17000774#comment-17000774
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Dawid Wysakowicz commented on FLINK-13910:
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1. As I said before I am in favor of not changing all classes in one go.
2. I'd prefer to target that for 1.11 rather than 1.10 as Aljoscha said
earlier, we should rather analyze if the classes need to be serializable than
just add serialVersionUID
3. I'd prefer to change the serialVersionUID to 1 rather than generated long
numbers
3. If we want to add serialVersionUID to *ALL* classes we need a way to enforce
that in the future. This must be incorporated into the build not process. An
inspection in IDEA is not enough for that.
> Many serializable classes have no explicit 'serialVersionUID'
> -------------------------------------------------------------
>
> Key: FLINK-13910
> URL: https://issues.apache.org/jira/browse/FLINK-13910
> Project: Flink
> Issue Type: Bug
> Components: API / Type Serialization System
> Reporter: Yun Tang
> Assignee: Yun Tang
> Priority: Critical
> Labels: pull-request-available
> Fix For: 1.9.2, 1.10.0
>
> Attachments: SerializableNoSerialVersionUIDField,
> serializable-classes-without-uid-5249249
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently, many serializable classes in Flink have no explicit
> 'serialVersionUID'. As [official
> doc|https://flink.apache.org/contributing/code-style-and-quality-java.html#java-serialization]
> said, {{Serializable classes must define a Serial Version UID}}.
> No 'serialVersionUID' would cause compatibility problem. Take
> {{TwoPhaseCommitSinkFunction}} for example, since no explicit
> 'serialVersionUID' defined, after
> [FLINK-10455|https://github.com/apache/flink/commit/489be82a6d93057ed4a3f9bf38ef50d01d11d96b]
> introduced, its default 'serialVersionUID' has changed from
> "4584405056408828651" to "4064406918549730832". In other words, if we submit
> a job from Flink-1.6.3 local home to remote Flink-1.6.2 cluster with the
> usage of {{TwoPhaseCommitSinkFunction}}, we would get exception like:
> {code:java}
> org.apache.flink.streaming.runtime.tasks.StreamTaskException: Cannot
> instantiate user function.
> at
> org.apache.flink.streaming.api.graph.StreamConfig.getStreamOperator(StreamConfig.java:239)
> at
> org.apache.flink.streaming.runtime.tasks.OperatorChain.<init>(OperatorChain.java:104)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:267)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:711)
> at java.lang.Thread.run(Thread.java:748)
> Caused by: java.io.InvalidClassException:
> org.apache.flink.streaming.api.functions.sink.TwoPhaseCommitSinkFunction;
> local class incompatible: stream classdesc serialVersionUID =
> 4584405056408828651, local class serialVersionUID = 4064406918549730832
> at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:699)
> at
> java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1885)
> at
> java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1751)
> at
> java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1885)
> at
> java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1751)
> at
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2042)
> at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
> at
> java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
> at
> java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
> at
> java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
> at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
> at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
> at
> org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:537)
> at
> org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:524)
> at
> org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:512)
> at
> org.apache.flink.util.InstantiationUtil.readObjectFromConfig(InstantiationUtil.java:473)
> at
> org.apache.flink.streaming.api.graph.StreamConfig.getStreamOperator(StreamConfig.java:224)
> ... 4 more
> {code}
> Similar problems existed in
> {{org.apache.flink.streaming.api.operators.SimpleOperatorFactory}} which has
> different 'serialVersionUID' from release-1.9 and current master branch.
> IMO, we might have two options to fix this bug:
> # Add explicit serialVersionUID for those classes which is identical to
> latest Flink-1.9.0 release code.
> # Use similar mechanism like {{FailureTolerantObjectInputStream}} in
> {{InstantiationUtil}} to ignore serialVersionUID mismatch.
> I have collected all production classes without serialVersionUID from latest
> master branch in the attachment, which counts to 639 classes.
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