Mastering High Performance with Kotlin

Range benchmarking

Since the IntRange class inherits from the IntProgression class which, in turn, implements the Iterable interface, we can invoke the forEach function:

(0..10).forEach {}

Decompiled to Java, the code looks like this:

public static final void main(@NotNull String[] args) {   Intrinsics.checkParameterIsNotNull(args, "args");   byte var1 = 0;   Iterable $receiver$iv = (Iterable)(new IntRange(var1, 10));   int element$iv;   for(Iterator var2 = $receiver$iv.iterator(); var2.hasNext(); element$iv = ((IntIterator)var2).nextInt()) {      ;   }}

Let's write it and run some benchmarks:

val range = 0..1_000val array = Array(1_000) { it }@Benchmarkfun rangeLoop(blackhole: Blackhole) {    range.forEach {        blackhole.consume(it)    }}@Benchmarkfun rangeSequenceLoop(blackhole: ...