JMH: Using the same static object in all Benchmark tests

Question

I have a class that constructs some complicated data (imagine a large XML or JSON structure - that sort of thing). Constructing it takes time. So I want to construct it once

Answer 1

I would just move all of your benchmark methods into one class, define your state object as an inner class, and inject the state to each of them:

public class ParserBenchmarks {

  @State(Scope.Thread)
  public static class StateHolder {
    Parser parser = null;

    @Setup(Level.Iteration)
    public void setup()
    {
      parser = new Parser(TestSet.PARSE_ME);
    }

    public Parser getParser() {
      return parser;
    }
  }

  @Benchmark
  public int getId_123(StateHolder stateHolder) {
    return stateHolder.getParser().getId(123);
  }

  @Benchmark
  public int getId_456(StateHolder stateHolder) {
    return stateHolder.getParser().getId(456);
  }

}

Note that all of your benchmark methods should return values otherwise the compiler could eliminate it as dead code.