Spring boot + webflux：并行运行某些步骤时上下文丢失

Question

Spring boot：2.1.3.RELEASE

你好，

我试图使用spring webflux的上下文功能来携带一个简单的变量。我有一个WebFilter设置一个带有这样的变量的上下文，我尝试在我的控制器中使用它在我的流量/流的不同阶段。在某些时候，我在调用Flux类的“parallel（）”方法后丢失了它。

• 过滤器：

public class TestFilter implements WebFilter {

    private Logger LOG = LoggerFactory.getLogger(TestFilter.class);

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
        return chain.filter(exchange)
            .doOnEach(voidSignal -> System.out.println("filter:"+voidSignal.getContext().getOrEmpty("blob"))).subscriberContext(Context.of("blob", "kapoue"));
    }

}

• 控制器：

@RestController
@RequestMapping(TestControllerWebFlux.ROOT)
public class TestControllerWebFlux {

    static final String ROOT = "/flux";
    static final String TEST = "/test";

    private WebClient webClient = WebClient.create();

    @GetMapping(
            value = TEST,
            produces = {MediaType.APPLICATION_JSON_VALUE})
    public Mono<String> test() {
        System.out.println("controller1:"+Thread.currentThread());

        Flux<String> call = webClient.get().uri("http://localhost:" + 8080 + ROOT + "/test2").retrieve().bodyToFlux(Result.class).map(Result::getValue);

        return call.map(s -> s+"0")
            .doOnEach(stringSignal -> System.out.println("controller2:"+stringSignal.getContext().getOrEmpty("blob")))
            .parallel()
            .doOnEach(stringSignal -> System.out.println("controller3:"+stringSignal.getContext().getOrEmpty("blob")))
            .map(s -> s+"0")
            .doOnEach(stringSignal -> System.out.println("controller4:"+stringSignal.getContext().getOrEmpty("blob")))
            .reduce((s, s2) -> s+s2)
            .doOnEach(stringSignal -> System.out.println("controller5:"+stringSignal.getContext().getOrEmpty("blob")))
            .map(s -> {
                System.out.println("controller6:"+Thread.currentThread());
                return s;
            });
    }

    @GetMapping(
        value = "test2",
        produces = {MediaType.APPLICATION_JSON_VALUE})
    public Flux<Result> test2() {
        return Flux.just(new Result("0"), new Result("0"), new Result("0"));
    }

    @Data
    @AllArgsConstructor
    @NoArgsConstructor
    public static class Result {
        private String value;
    }
}

我所做的只是调用http://localhost:8080/flux/test/端点，我得到了：

controller1：Thread [reactor-http-nio-2,5，main] controller2：可选[kapoue] controller3：Optional.empty controller4：Optional.empty controller2：可选[kapoue] controller3：Optional.empty controller4：Optional.empty controller2：可选[kapoue] controller3：Optional.empty controller4：Optional.empty controller2：可选[kapoue] controller3：Optional.empty controller4：Optional.empty controller3：Optional.empty controller4：Optional.empty controller3：Optional.empty controller4：Optional.empty controller3：Optional.empty controller4：Optional.empty controller5：可选[kapoue] controller6：Thread [reactor-http-nio-2,5，main]过滤器：可选[kapoue]

正如您所看到的，上下文在“并行”方法之后立即丢失，并在减少之后以某种方式返回。

这是一个错误还是我不应该在这样的电话之后尝试并行运行？

提前感谢您的帮助。

Answer 1

这看起来像Reactor中的一个错误。我报告了：https://github.com/reactor/reactor-core/issues/1656