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ASF GitHub Bot commented on FLINK-8264: --------------------------------------- GitHub user StephanEwen opened a pull request: https://github.com/apache/flink/pull/5167 [FLINK-8264] [core] Add 'scala.' to the 'parent-first' classloading patterns **BACKPORT of #5166 to release-1.4** ## What is the purpose of the change Adding `scala.` to the "parent-first-patterns" makes sure that Scala classes are not duplicated through "child-first" classloading when users accidentally package the Scala Library into the application jar. Since Scala classes traverse the boundary between core and user space, they should never be duplicated. ## Brief change log - Adds `scala.` to the default value of `classloader.parent-first-patterns`. ## Verifying this change This change can be verified as follows: - Create a very simple quickstart Scala project using a Scala lambda for a filter function (`_ => true`). - Package it such that the Scala library is in the user code jar - Without the fix, you get a weird class cast exception during deserialization, with this fix, everything is fine. ## Does this pull request potentially affect one of the following parts: - Dependencies (does it add or upgrade a dependency): (yes / **no)** - The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (yes / **no**) - The serializers: (yes / **no** / don't know) - The runtime per-record code paths (performance sensitive): (yes / **no** / don't know) - Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / **no** / don't know) - The S3 file system connector: (yes / **no** / don't know) ## Documentation - Does this pull request introduce a new feature? (yes / **no**) - If yes, how is the feature documented? (**not applicable** / docs / JavaDocs / not documented) You can merge this pull request into a Git repository by running: $ git pull https://github.com/StephanEwen/incubator-flink 8264_backport Alternatively you can review and apply these changes as the patch at: https://github.com/apache/flink/pull/5167.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #5167 ---- commit 8bd70c1e3d31f5c285ac5995504e52e39063e90b Author: Stephan Ewen <se...@apache.org> Date: 2017-12-14T12:50:39Z [FLINK-8264] [core] Add 'scala.' to the 'parent-first' classloading patterns. ---- > Add Scala to the parent-first loading patterns > ---------------------------------------------- > > Key: FLINK-8264 > URL: https://issues.apache.org/jira/browse/FLINK-8264 > Project: Flink > Issue Type: Improvement > Components: Core > Affects Versions: 1.4.0 > Reporter: Stephan Ewen > Assignee: Stephan Ewen > Fix For: 1.5.0, 1.4.1 > > > A confusing experience happens when users accidentally package the Scala > Library into their jar file. The reversed class loading duplicates Scala's > classes, leading to exceptions like the one below. > By adding {{scala.}} to the default 'parent-first-patterns' we can improve > the user experience in such situations. > Exception Stack Trace: > {code} > java.lang.ClassCastException: cannot assign instance of > org.peopleinmotion.TestFunction$$anonfun$1 to field > org.apache.flink.streaming.api.scala.DataStream$$anon$7.cleanFun$6 of type > scala.Function1 in instance of > org.apache.flink.streaming.api.scala.DataStream$$anon$7 > at > java.io.ObjectStreamClass$FieldReflector.setObjFieldValues(ObjectStreamClass.java:2233) > at > java.io.ObjectStreamClass.setObjFieldValues(ObjectStreamClass.java:1405) > at > java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2288) > at > java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2206) > at > java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2064) > at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1568) > at > java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2282) > at > java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2206) > at > java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2064) > at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1568) > at java.io.ObjectInputStream.readObject(ObjectInputStream.java:428) > at > org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:290) > at > org.apache.flink.util.InstantiationUtil.readObjectFromConfig(InstantiationUtil.java:248) > at > org.apache.flink.streaming.api.graph.StreamConfig.getStreamOperator(StreamConfig.java:220) > ... 6 more > {code} -- This message was sent by Atlassian JIRA (v6.4.14#64029)