Github user kiszk commented on a diff in the pull request:
https://github.com/apache/spark/pull/16391#discussion_r93826236
--- Diff:
sql/core/src/test/scala/org/apache/spark/sql/DatasetBenchmark.scala ---
@@ -170,36 +176,39 @@ object DatasetBenchmark {
val benchmark3 = aggregate(spark, numRows)
/*
- OpenJDK 64-Bit Server VM 1.8.0_91-b14 on Linux
3.10.0-327.18.2.el7.x86_64
- Intel Xeon E3-12xx v2 (Ivy Bridge)
+ Java HotSpot(TM) 64-Bit Server VM 1.8.0_60-b27 on Mac OS X 10.12.1
+ Intel(R) Core(TM) i7-4960HQ CPU @ 2.60GHz
+
back-to-back map: Best/Avg Time(ms)
Rate(M/s) Per Row(ns) Relative
------------------------------------------------------------------------------------------------
- RDD 3448 / 3646 29.0
34.5 1.0X
- DataFrame 2647 / 3116 37.8
26.5 1.3X
- Dataset 4781 / 5155 20.9
47.8 0.7X
+ RDD 3963 / 3976 25.2
39.6 1.0X
+ DataFrame 826 / 834 121.1
8.3 4.8X
+ Dataset 5178 / 5198 19.3
51.8 0.8X
--- End diff --
I noticed that Scala compiler automatically generates primitive version.
Current Spark eventually calls primitive version thru generic version `Object
apply(Object)`.
Here is a simple example. When we compile the following sample, we can find
that the following class is generated by scalac. Scalac automatically generates
a primitive version `int apply$mcII$sp(int)` that can be called by `int
apply(int)`.
We could infer this signature in Catalyst for simple cases.
Of course, I totally agree that the best solution is to analyze byte code
and turn it into expression. [This
](https://issues.apache.org/jira/browse/SPARK-14083)was already prototyped. Do
you think it is good time to make this prototype more robust now?
```java
test("ds") {
val ds = sparkContext.parallelize((1 to 10), 1).toDS
ds.map(i => i * 7).show
}
$ javap -c Test\$\$anonfun\$5\$\$anonfun\$apply\$mcV\$sp\$1.class
Compiled from "Test.scala"
public final class
org.apache.spark.sql.Test$$anonfun$5$$anonfun$apply$mcV$sp$1 extends
scala.runtime.AbstractFunction1$mcII$sp implements scala.Serializable {
public static final long serialVersionUID;
public final int apply(int);
Code:
0: aload_0
1: iload_1
2: invokevirtual #18 // Method apply$mcII$sp:(I)I
5: ireturn
public int apply$mcII$sp(int);
Code:
0: iload_1
1: bipush 7
3: imul
4: ireturn
public final java.lang.Object apply(java.lang.Object);
Code:
0: aload_0
1: aload_1
2: invokestatic #29 // Method
scala/runtime/BoxesRunTime.unboxToInt:(Ljava/lang/Object;)I
5: invokevirtual #31 // Method apply:(I)I
8: invokestatic #35 // Method
scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
11: areturn
public
org.apache.spark.sql.Test$$anonfun$5$$anonfun$apply$mcV$sp$1(org.apache.spark.sql.Test$$anonfun$5);
Code:
0: aload_0
1: invokespecial #42 // Method
scala/runtime/AbstractFunction1$mcII$sp."<init>":()V
4: return
}
```
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