将 DeferredResult 和 RxJava 与 Spring MVC 一起使用时性能降低

Question

我一直在尝试将 DeferredResult 和 RxJava 与 Spring MVC 集成可能带来的性能影响。请注意，与 rx 端点相比，norx 端点的性能下降。我期待 RxJava + DeferredResult 实现优于普通版本（请求数，req/sec）。谁能解释为什么会这样？

使用以下代码： https://gist.github.com/richardkabiling/b53eae46c4414d4341ef310bf3a070c1

@Controller
public class SumController {

    SecureRandom random = new SecureRandom();

    @RequestMapping(value = "/init")
    public ResponseEntity<Void> init() {
        return ResponseEntity.ok(null);
    }

    @RequestMapping(value = "/norx1")
    public ResponseEntity<BigDecimal> simpleSync() {
        return ResponseEntity.ok(getA());
    }

    @RequestMapping(value = "/rx1")
    public DeferredResult<ResponseEntity<BigDecimal>> simpleAsync() {
        DeferredResult<ResponseEntity<BigDecimal>> result = new DeferredResult<>();
        Observable.create(emit(this::getA))
            .map(n -> ResponseEntity.ok(n))
            .subscribe(re -> result.setResult(re));
        return result;
    }

    @RequestMapping(value = "/norx2")
    public ResponseEntity<BigDecimal> sync() {
        return ResponseEntity.ok(getA().add(getB()));
    }

    @RequestMapping(value = "/rx2")
    public DeferredResult<ResponseEntity<BigDecimal>> async() {
        DeferredResult<ResponseEntity<BigDecimal>> result = new DeferredResult<>();
        Observable.create(emit(this::getA))
                .zipWith(Observable.create(emit(this::getB)), (x, y) -> x.add(y))
                .map(n -> ResponseEntity.ok(n))
                .subscribe(re -> result.setResult(re));
        return result;
    }


    private Observable.OnSubscribe<BigDecimal> emit(Supplier<? extends BigDecimal> p) {
        return s -> {
            s.onNext(p.get());
            s.onCompleted();
        };
    }

    private BigDecimal getA() {
        sleep();
        return BigDecimal.valueOf(500);
    }

    private BigDecimal getB() {
        sleep();
        return BigDecimal.valueOf(300);
    }

    private void sleep() {
        try { Thread.sleep(10 + random.nextInt(10)); } catch (InterruptedException e) { }
    }
}

我得到了以下性能结果（使用wrk）：

Running 10s test @ http://localhost:8080/norx1
  10 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    78.11ms   31.32ms 250.18ms   67.27%
    Req/Sec   307.06     68.75   474.00     65.60%
  30663 requests in 10.05s, 4.98MB read
  Socket errors: connect 759, read 129, write 0, timeout 0
Requests/sec:   3052.35
Transfer/sec:    507.18KB

Running 10s test @ http://localhost:8080/rx1
  10 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    86.67ms   38.32ms 313.65ms   67.19%
    Req/Sec   277.84    101.59   565.00     73.37%
  27732 requests in 10.08s, 4.50MB read
  Socket errors: connect 759, read 0, write 0, timeout 0
Requests/sec:   2749.94
Transfer/sec:    456.98KB

Running 10s test @ http://localhost:8080/norx2
  10 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    77.19ms   21.17ms 224.72ms   67.65%
    Req/Sec   311.54    174.18   770.00     68.80%
  31115 requests in 10.09s, 5.05MB read
  Socket errors: connect 759, read 116, write 0, timeout 0
Requests/sec:   3084.71
Transfer/sec:    512.57KB

Running 10s test @ http://localhost:8080/rx2
  10 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    86.05ms   27.78ms 226.40ms   64.60%
    Req/Sec   554.96    387.63     1.28k    55.13%
  27761 requests in 10.07s, 4.51MB read
  Socket errors: connect 759, read 102, write 0, timeout 0
Requests/sec:   2756.15
Transfer/sec:    458.01KB

Answer 1

在进一步尝试之后，我遇到的主要问题似乎是我选择的延迟（~20ms）太小而无法利用 Spring MVC + RxJava 中的异步操作。增加到约 500 毫秒就可以解决问题，并显示出巨大的性能改进。