[jira] [Created] (FLINK-9654) Internal error while deserializing custom Scala TypeSerializer instances

["Zsolt Donca (JIRA)" <ji...@apache.org>]

Zsolt Donca created FLINK-9654:
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             Summary: Internal error while deserializing custom Scala TypeSerializer instances
                 Key: FLINK-9654
                 URL: https://issues.apache.org/jira/browse/FLINK-9654
             Project: Flink
          Issue Type: Bug
            Reporter: Zsolt Donca


When you are using custom `TypeSerializer` instances implemented in Scala, the Scala issue [SI-2034|https://issues.scala-lang.org/browse/SI-2034] can manifest itself when a Flink job is restored from checkpoint or started with a savepoint.

The reason is that in such a restore from checkpoint or savepoint, Flink uses `InstantiationUtil.FailureTolerantObjectInputStream` to deserialize the type serializers and their configurations. The deserialization walks through the entire object graph corresponding, and for each class it calls `isAnonymousClass`, which, in turn, calls `getSimpleName` (mechanism in place for FLINK-6869). If there is an internal class defined in a Scala object for which `getSimpleName` fails (see the Scala issue), then a `java.lang.InternalError` is thrown which causes the task manager to restart. In this case, Flink tries to restart the job on another task manager, causing all the task managers to restart, wreaking havoc on the entire Flink cluster.

There are some alternative type information derivation mechanisms that rely on anonymous classes and, most importantly, classes generated by macros, that can easily trigger the above problem. I am personally working on [flink-alt|[https://github.com/zsolt-donca/flink-alt]|https://github.com/zsolt-donca/flink-alt],], and there is also [flink-shapeless|[https://github.com/joroKr21/flink-shapeless].]

I prepared a pull request that fixes the issue. 



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