StringPerformance BenchMark :: building strings within loops :: 10K increment to 100K

StringPerf.java

import java.util.Random;
import java.util.concurrent.TimeUnit;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;
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;

/**
 * @implNote :: run with java -jar benchmarks.jar StringPerf -wi 10 -i 10 -f 4
 * @author Edward Beckett <[email protected]>
 * @since 12/24/2015
 */
@State(Scope.Thread)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class StringPerf {

    private int[] data;

    @Param({"10000", "20000", "30000", "40000", "50000", "60000", "70000", "80000", "90000", "100000"})
    private int reps;

    @Setup
    public void init() {
        reps = this.reps;
    }

    @Benchmark
    public void assignmentBench(Blackhole bh) {
        assignment(reps);
        bh.consume(reps);
    }

    @Benchmark
    public void builderBench(Blackhole bh) {
        builder(reps);
        bh.consume(reps);
    }

    @Benchmark
    public void concatBench(Blackhole bh) {
        concat(reps);
        bh.consume(reps);
    }


    static void assignment(int rep) {
        int x = 0;
        String s = "String ";
        while (x < rep) {
            s += "String ";
            ++x;
        }
    }

    static void builder(int rep) {
        int x = 0;
        StringBuilder builder = new StringBuilder("String ");
        while (x < rep) {
            builder.append("String ");
            ++x;
        }
    }

    static void concat(int rep) {
        int x = 0;
        String s = "String ";
        while (x < rep) {
            s = s.concat("String ");
            ++x;
        }

    }

    public static void main(String[] args) throws RunnerException {

        Options opt = new OptionsBuilder()
                .include(StringPerf.class.getSimpleName())
                .warmupIterations(10)
                .measurementIterations(10)
                .forks(4)
                .build();

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

StringPerfResults.csv