IntOverflowPuzzleJmh.java

package ru.int_overflow;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Benchmark)
public class IntOverflowPuzzleJmh {

    @GenerateMicroBenchmark
    public int count_int_to_max() {
        int counter = 0;
        int max = Integer.MAX_VALUE;
        while (counter != max) {
            ++counter;
        }
        return counter;
    }

    @GenerateMicroBenchmark
    public int count_int_overflow() {
        int counter = 0;
        int max = Integer.MAX_VALUE + 1; // <- It is overflow! to Integer.MIN_VALUE!
        while (counter != max) {
            ++counter;
        }
        return counter;
    }

    @GenerateMicroBenchmark
    public long count_long() {
        long counter = 0;
        int max = Integer.MAX_VALUE;
        while (counter != max) {
            ++counter;
        }
        return counter;
    }

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(".*" + IntOverflowPuzzleJmh.class.getSimpleName() + ".*")
//                .verbosity(VerboseMode.SILENT)
                .warmupIterations(3)
                .measurementIterations(5)
                .threads(1)
                .forks(1)
                .build();

        new Runner(opt).run();
    }
}

Intel Core i7, Ubuntu 12.0 LTS, Java 7

Benchmark Mode Samples Score Score error Units
o.s.MyBenchmark.count_int_overflow avgt 200 817931688.065 7959319.632 ns/op
o.s.MyBenchmark.count_int_to_max avgt 200 0.588 0.007 ns/op
o.s.MyBenchmark.count_long avgt 200 640244617.558 25173704.966 ns/op