caican00 commented on PR #37876:
URL: https://github.com/apache/spark/pull/37876#issuecomment-1283576673
> > I haven't thought of a better way yet
>
> Thanks. I'll share it with you if I can think of a better way
@LuciferYang
I have a question , why `ArrayBasedMapData#toScalaMap` method return
immutable.Map type rather than mutable.Map type?
I write a simple case to compare `building mutable.Map` and `building
immutable.Map` and `building mutable.Map` is about twice as fast as `building
immutable`.
test code:
```
case class Test(id: Int, name: String)
// build immutable.Map
val builder = immutable.Map.newBuilder[Test, String]
var index: Int = 0
val start = System.currentTimeMillis()
while (index < 10000000) {
builder += (Test(index, s"$index _ $index"),
index.toString).asInstanceOf[(Test, String)]
index += 1
}
builder.result()
val end = System.currentTimeMillis()
// scalastyle:off println
println(s"immutable map spent time: ${(end - start)/1000}s")
// scalastyle:off println
// build mutable.Map
val map = mutable.Map[Test, String]()
index = 0
val start1 = System.currentTimeMillis()
while (index < 10000000) {
map.put(Test(index, s"$index _ $index"), index.toString)
index += 1
}
val end1 = System.currentTimeMillis()
// scalastyle:off println
println(s"mutable map spent time: ${(end1 - start1)/1000}s")
// scalastyle:off println
```
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