是否可以并行启动 Mono 并汇总结果 [英] Is it possible to start Mono's in parallel and aggregate the result

问题描述

我知道可以链接 Mono，例如...

I know it is possible to chain Mono's, for ex,...

Mono<String> resultAMono = loadA();
Mono<String> resultBMono = resultA.flatMap(resultA -> loadB());

这将链接并且 resultBMono 将在 resultAMono 返回时运行....

This will chain and resultBMono will run when resultAMono returns....

所以我的问题是，是否可以并行启动 2 个 Mono，并且当两个返回都继续使用另一个 Mono 时?

So my question is, is it possible to start 2 Mono's in parallel and when both returns continue with another Mono?

我认为它看起来像这样......

I think it will look something like this...

Mono<String> resultAMono = loadA();
Mono<String> resuktBMono = loadB();
Mono<Tuple2<Stirng, String> tupleMono = Mono.zip(resultAMono, resultBMono);

但我不知道这会并行运行，或者我可以做些什么来并行运行...

but I have no idea this will run in Parallel or what can I do this to run in parallel...

感谢回答....

推荐答案

2个语义，1个让它们并行运行的方法

我在下面介绍的两个选项都需要一些额外的调整才能使 A 和 B Mono 并行运行:即，每个 Mono 应该使用 subscribeOn(Scheduler) 从它们合并的地方脱离公共线程.

The two options I present below both need some additional tuning to make A and B Mono run in parallel: namely, each Mono should use subscribeOn(Scheduler) to get out of the common thread from where they're merged.

如果你只关心A和B的完成

使用 when 来监听 A 和 B 完成，then 继续使用完全不同的 Mono:

Use when to listen for A and B completion and then to continue with a completely different Mono:

Mono.when(monoAwithSubscribeOn, monoBwithSubscribeOn)
    .then(Mono.just("A and B finished, I don't know their value"));

如果您关心 A 和 B 值

根据您想要对结果做什么，使用 zip + map/flatMap.

Use zip + map/flatMap depending on what you want to do with the result.

Mono.zip(monoAwithSubscribeOn, monoBwithSubscribeOn)
    .map(tuple2 -> new Foo(tuple2.getT1(), tuple2.getT2(), "bar");

或

Mono.zip(monoAwithSubscribeOn, monoBwithSubscribeOn)
    .flatMap(tuple2 -> fetchMoreDataAsMono(tuple2.getT1(), tuple2.getT2()));

then 会忽略前面的数据，所以在它之前使用 zip 没有多大意义.

then will ignore the previous data, so it wouldn't make much sense to use zip before it.

此外，如果 A 或 B 之一为空，zip 将导致 空 Mono！使用 switchIfEmpty/defaultIfEmpty 来防止这种情况.

also, zip will result in an empty Mono if one of A or B is empty! Use switchIfEmpty/defaultIfEmpty to protect against that case.

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