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https://issues.apache.org/jira/browse/SPARK-10877?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Patrick Wendell updated SPARK-10877:
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Assignee: Davies Liu
> Assertions fail straightforward DataFrame job due to word alignment
> -------------------------------------------------------------------
>
> Key: SPARK-10877
> URL: https://issues.apache.org/jira/browse/SPARK-10877
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 1.5.0
> Reporter: Matt Cheah
> Assignee: Davies Liu
> Attachments: SparkFilterByKeyTest.scala
>
>
> I have some code that I’m running in a unit test suite, but the code I’m
> running is failing with an assertion error.
> I have translated the JUnit test that was failing, to a Scala script that I
> will attach to the ticket. The assertion error is the following:
> {code}
> Exception in thread "main" org.apache.spark.SparkException: Job aborted due
> to stage failure: Task 0 in stage 0.0 failed 1 times, most recent failure:
> Lost task 0.0 in stage 0.0 (TID 0, localhost): java.lang.AssertionError:
> lengthInBytes must be a multiple of 8 (word-aligned)
> at
> org.apache.spark.unsafe.hash.Murmur3_x86_32.hashUnsafeWords(Murmur3_x86_32.java:53)
> at
> org.apache.spark.sql.catalyst.expressions.UnsafeArrayData.hashCode(UnsafeArrayData.java:289)
> at
> org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow$class.hashCode(rows.scala:149)
> at
> org.apache.spark.sql.catalyst.expressions.GenericMutableRow.hashCode(rows.scala:247)
> at org.apache.spark.HashPartitioner.getPartition(Partitioner.scala:85)
> at
> org.apache.spark.sql.execution.Exchange$$anonfun$doExecute$1$$anonfun$4$$anonfun$apply$4.apply(Exchange.scala:180)
> at
> org.apache.spark.sql.execution.Exchange$$anonfun$doExecute$1$$anonfun$4$$anonfun$apply$4.apply(Exchange.scala:180)
> at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
> {code}
> However, it turns out that this code actually works normally and computes the
> correct result if assertions are turned off.
> I traced the code and found that when hashUnsafeWords was called, it was
> given a byte-length of 12, which clearly is not a multiple of 8. However, the
> job seems to compute correctly regardless of this fact. Of course, I can’t
> just disable assertions for my unit test though.
> A few things we need to understand:
> 1. Why is the lengthInBytes of size 12?
> 2. Is it actually a problem that the byte length is not word-aligned? If so,
> how should we fix the byte length? If it's not a problem, why is the
> assertion flagging a false negative?
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