How to catch/detect exceptions in multi-threaded map/reduce using Reactor framework 2.x?

问题

I was playing with the code of this answer and it works smoothly. However, if an exception is thrown, the caller code does not catch it.

How is an Exception captured in reactor 2.0 streams? What I want to do is: if an Exception is thrown, stream processing must stop. I need to throw the Exception up in the caller thread (the one that created the steam in first place).

List<Map<String, Object>> data = readData(); 

Streams.from(data)
       .flatMap(m -> Streams.just(m)
                            .dispatchOn(Environment.cachedDispatcher()) 
                            .map(ignored -> {throw new RuntimeException("kaboom!");}))
       .buffer() 
       .consume(s -> System.out.println("s: " + s)); 
// the exception is not thrown and there is not opportunity to deal with it.

回答1:

In Reactor you just need to wrap exceptions and return them as Flux.error()

Then you can handle them in onErrorXXX methods (eg. onErrorResume)

See more:

https://projectreactor.io/docs/core/release/reference/#error.handling

来源：https://stackoverflow.com/questions/27976372/how-to-catch-detect-exceptions-in-multi-threaded-map-reduce-using-reactor-framew