api调用链接达到一定限制Rxjava2 + Retrofit2

Question

I'm using Retrofit2 with Rxjava to make API calls. I have to make multiple API calls ( of the same API ), let's say 100 of them. Now I want, at max 5 of them to be executed parallelly. So if 5 API calls are going on, 6th one should wait. As soon as any one of those ongoing 5 calls is completed, 6th one should start. I don't want this in bulk of 5 where first 5 completes and only after that next 5 happens.

I'm not sure how can I achieve with Rxjava and that's why I don't have any snippet to post. Any help would be great

Answer 1

RxJava has certain operators that can limit the number of threads in action.

observable
  .flatMap( input -> apiCallReturningObservable( input ), 5 )
  .subscribe();

will have a maximum of 5 invocations of apiCallReturningObservable() at one time.