[jira] [Created] (FLINK-13910) Many serializable classes have no explicit 'serialVersionUID'

["Yun Tang (Jira)" <ji...@apache.org>]

Yun Tang created FLINK-13910:
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             Summary: Many serializable classes have no explicit 'serialVersionUID'
                 Key: FLINK-13910
                 URL: https://issues.apache.org/jira/browse/FLINK-13910
             Project: Flink
          Issue Type: Bug
            Reporter: Yun Tang
         Attachments: SerializableNoSerialVersionUIDField

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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