[jira] [Assigned] (ARROW-3175) [Java] Upgrade to official FlatBuffers release (Flatbuffers incompatibility)

["Kouhei Sutou (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-3175?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kouhei Sutou reassigned ARROW-3175:
-----------------------------------

    Assignee: Li Jin

> [Java] Upgrade to official FlatBuffers release (Flatbuffers incompatibility)
> ----------------------------------------------------------------------------
>
>                 Key: ARROW-3175
>                 URL: https://issues.apache.org/jira/browse/ARROW-3175
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Java
>    Affects Versions: 0.10.0
>            Reporter: Alex Black
>            Assignee: Li Jin
>            Priority: Blocker
>              Labels: pull-request-available
>             Fix For: 0.11.0
>
>          Time Spent: 7h 50m
>  Remaining Estimate: 0h
>
> Arrow Java currently uses an unofficial flatbuffers dependency - com.vlkan:flatbuffers:
>  [https://github.com/apache/arrow/blob/master/java/pom.xml#L481-L485]
> The likely motivation here is that previously, no Java flatbuffers implementation was available on maven central.
>  [https://github.com/vy/flatbuffers]
>  > Unfortunately, FlatBuffers project does not publish any artifacts to the Maven Central Repository
> However, this is no longer the case:
>  [https://search.maven.org/search?q=g:com.google.flatbuffers%20AND%20a:flatbuffers-java&core=gav]
> The flatbuffers version used in Arrow java is a nearly 3-year-old snapshot, not even a version of an official release: [https://github.com/vy/flatbuffers#usage]
> The main problem is that this version of flatbuffers is not compatible with the official releases of flatbuffers.
>  For example, we use the official flatbuffers releases in ND4J and Deeplearning4j: [https://github.com/deeplearning4j/deeplearning4j]
> Running Arrow with an official flatbuffers library on the classpath results in issues such as:
> {noformat}
> java.lang.NoSuchMethodError: com.google.flatbuffers.FlatBufferBuilder.createString(Ljava/lang/String;)I
>  at org.apache.arrow.vector.types.pojo.Field.getField(Field.java:154)
>  at org.apache.arrow.vector.types.pojo.Schema.getSchema(Schema.java:145)
>  at org.apache.arrow.vector.ipc.message.MessageSerializer.serialize(MessageSerializer.java:124)
>  at org.apache.arrow.vector.ipc.ArrowWriter.ensureStarted(ArrowWriter.java:136)
>  at org.apache.arrow.vector.ipc.ArrowWriter.start(ArrowWriter.java:97)
>  at FlatBuffersDependencyIssue.test(FlatBuffersDependencyIssue.java:56)
> {noformat}
>  
> Simply excluding the com.vlkan:flatbuffers dependency in lieu of an official flatbuffers release is not a solution (same exception as above) and we aren't prepared to downgrade all of our projects to use the flatbuffers version that Arrow currently requires.
>  Consequently, this is a major issue that prevents us using Arrow in our libraries.
> I have prepared a simple repository to reproduce this issue, if required: [https://github.com/AlexDBlack/arrowflatbufferstest]
> Is there a reason for using this particular version of flatbuffers, and if not, can Arrow java use an official release of flatbuffers instead?



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