string intern benchmark with JMH

StringInternTest.java

package jmh;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.profile.GCProfiler;
import org.openjdk.jmh.profile.StackProfiler;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;

@State(Scope.Thread)
public
class StringInternTest {

    private static final int batch_size = 300_000;

    private List<String> lst = new ArrayList();

    @Setup(Level.Iteration)
    public void setup(){
      lst.clear();
   }

    @Benchmark
    public List<String> withoutStringIntern() {
        lst.add(String.valueOf(lst.size() % 100));
          return lst;
    }

    @Benchmark
    public List<String> withStringIntern() {
        lst.add(String.valueOf(lst.size() % 100).intern());
        return lst;
    }

    public static void main(String ...args) throws Exception {

        Options opts = new OptionsBuilder()
                .include(StringInternTest.class.getSimpleName())
                .forks(1)
                .warmupIterations(5)
                .warmupBatchSize(batch_size)
                .mode(Mode.SingleShotTime)
                .timeUnit(TimeUnit.MILLISECONDS)
                .measurementIterations(20)
                .measurementBatchSize(batch_size)
                .addProfiler(GCProfiler.class)
                .addProfiler(StackProfiler.class)
                .jvmArgs("-server", "-Xmx128m", "-Xms128m")
                .build();

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