What backpressure manifests in practice is bounded buffers, Flowable.observeOn has a buffer of 128 elements that gets drained as fast as the dowstream can take it. You can increase this buffer size individually to handle bursty source and all the backpressure-management practices still apply from 1.x. Observable.observeOn has an unbounded buffer that keeps collecting the elements and your app may run out of memory.
You may use Observable for example:
- handling GUI events
- working with short sequences (less than 1000 elements total)
You may use Flowable for example:
- cold and non-timed sources
- generator like sources
- network and database accessors