Why is Spring MVC json serialization 10x slower than calling jackson manually?

Question

Using apachebench with "ab -k -c 50 -n 1000000" options (50 concurrent threads) shows a 10x performance difference between the following 2 methods (manual and spring-managed serialization). Is it possible to achieve the same performance via configuration of Spring serialization?

I'm running the test on Windows 7, JDK8, i7-6700. Embedded Tomcat, similar results with Undertow or Jetty too. A similar WildFly 10 JAX-RS sample apps performance yields similar results as the manual spring one, so I see no reason why Spring automatic mode should be so slow.

Full source code:

@SpringBootApplication
@Controller
public class DemoApplication {

  public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
  }

  ObjectMapper mapper = new ObjectMapper(new JsonFactory());

  @RequestMapping(value = "/auto", produces = "application/json; charset=utf-8")
  @ResponseBody
  public Lol automaticSerialization() {

    Lol lol = new Lol();
    lol.a = UUID.randomUUID().toString();
    lol.b = System.currentTimeMillis();

    return lol;
  }

  @RequestMapping(value = "/manual", produces = "application/json; charset=utf-8")
  @ResponseBody
  public String manualSerialization() throws JsonProcessingException {

    Lol lol = new Lol();
    lol.a = UUID.randomUUID().toString();
    lol.b = System.currentTimeMillis();

    return mapper.writeValueAsString(lol);
  }

  public static class Lol {

    String a;
    long b;

    public void setA(String a) {
      this.a = a;
    }

    public void setB(long b) {
      this.b = b;
    }

    public String getA() {
      return a;
    }

    public long getB() {
      return b;
    }
  }

}

Edit: Trace of automatic serialization:

Trace of manual serialization:

Answer 1

The only idea that I have is that Spring's default ObjectMapper is configured a bit differently than the one you use in your benchmark. Like the comments mention, you'd probably see a bit of overhead if you let Spring handle the mapping automatically but it shouldn't have more than a few percent's worth of impact.

To be sure that the comparison is fair, add this bean definition to your configuration:

@Bean
@Primary
ObjectMapper objectMapper() {
    return new ObjectMapper(new JsonFactory());
}

and replace ObjectMapper mapper = new ObjectMapper(new JsonFactory()); with an autowired field:

@Autowired
ObjectMapper mapper;

and see if the benchmarks return the same value.

EDIT

I wanted to verify this for myselt so I wrote a JMeter plan and executed each endpoint exactly 5kk times, with a 1-minute warm-up period. The results were as expected, no major differences between the approaches:

Label,# Samples,Average,Min,Max,Std. Dev.,Error %,Throughput,KB/sec,Avg. Bytes
Auto Request,5000000,2,0,108,5.88,0.00%,15577.3,3088.08,203.0
Manual Request,5000000,2,0,149,5.99,0.00%,15660.2,2813.94,184.0

The important thing to note is the throughput difference - auto's 15577.3 vs. manual's 15660.2.

Here's my JMeter test plan, if you'd like to test it yourself, I was running on port 8081. If I find the time, I'll try another benchmarking framework, perhaps Gatling.