[jira] [Created] (SPARK-16331) [SQL] Reduce code generation time

["Hiroshi Inoue (JIRA)" <ji...@apache.org>]

Hiroshi Inoue created SPARK-16331:
-------------------------------------

             Summary: [SQL] Reduce code generation time 
                 Key: SPARK-16331
                 URL: https://issues.apache.org/jira/browse/SPARK-16331
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 2.0.0, 2.1.0
            Reporter: Hiroshi Inoue


During the code generation, a {{LocalRelation}} often has a huge {{Vector}} object as {{data}}. In the simple example below, a {{LocalRelation}} has a Vector with 1000000 elements of {{UnsafeRow}}. 

{quote}
val numRows = 1000000
val ds = (1 to numRows).toDS().persist()
benchmark.addCase("filter+reduce") { iter =>
  ds.filter(a => (a & 1) == 0).reduce(_ + _)
}
{quote}

At {{TreeNode.transformChildren}}, all elements of the vector is unnecessarily iterated to check whether any children exist in the vector since {{Vector}} is Traversable. This part significantly increases code generation time.

This patch avoids this overhead by checking the number of children before iterating all elements; {{LocalRelation}} does not have children since it extends {{LeafNode}}.

The performance of the above example 
{quote}
without this patch
Java HotSpot(TM) 64-Bit Server VM 1.8.0_91-b14 on Mac OS X 10.11.5
Intel(R) Core(TM) i5-5257U CPU @ 2.70GHz
compilationTime:                         Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
filter+reduce                                 4426 / 4533          0.2        4426.0       1.0X

with this patch
compilationTime:                         Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
filter+reduce                                 3117 / 3391          0.3        3116.6       1.0X
{quote}




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