[ueshin]

Original problem is SPARK-3764.

AppendingParquetOutputFormat uses a binary-incompatible method context.getTaskAttemptID.
This causes binary-incompatible of Spark itself, i.e. if Spark itself is built against hadoop-1, the artifact is for only hadoop-1, and vice versa.

[AmplabJenkins]

Test FAILed.
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[SparkQA]

QA tests have started for PR 2638 at commit ec213c1.

• This patch merges cleanly.

[SparkQA]

QA tests have finished for PR 2638 at commit ec213c1.

• This patch passes unit tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • println(s"Failed to load main class $childMainClass.")
  • case class GetPeers(blockManagerId: BlockManagerId) extends ToBlockManagerMaster

[srowen]

A particular instance of Spark will be built for a particular version of Hadoop and/or YARN. It is not at this point a universal binary anyway, and so, I do not think it is necessary to add this indirection via reflection. That is, if you are deploying on Hadoop 1, you need to build Spark for Hadoop 1, and similarly for Hadoop 2.

[ueshin]

@srowen, Thank you for your comment.
Indeed, when deploy completed apps to Spark cluster, there is a particular instance of Spark.
But Spark app developers will use artifacts in Maven Central while developing and unit-testing. The artifacts seem to be built for Hadoop 2, so if they want to test with Hadoop 1, it won't work.
What do you think?

[marmbrus]

@ueshin I'm not sure I fully understand. What are the two method signatures in question such that it compiles but then fails at runtime. Can you perhaps include these details in a comment?

@srowen are you satisfied with that explanation?

[AmplabJenkins]

Can one of the admins verify this patch?

[ueshin]

@marmbrus, Thank you for your comment.
The TaskAttemptContext is a class in hadoop-1 but is an interface in hadoop-2.
The signatures of the method TaskAttemptContext.getTaskAttemptID for the both versions are the same, so the method calls are source-compatible but NOT binary-compatible because the opcode of method call for class is INVOKEVIRTUAL and for interface is INVOKEINTERFACE.

[SparkQA]

QA tests have started for PR 2638 at commit efd3784.

• This patch merges cleanly.

[SparkQA]

QA tests have finished for PR 2638 at commit efd3784.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

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Test PASSed.
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[marmbrus]

Thanks! Merged.