scala - Is blocking within a future still blocking? -

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blocking bad, async good, blocking within future still blocking? keep coming to; consider following pseudo-code:

def queryname(id:id):future[string] def queryeveryonesnames:future[seq[string]] = {   val everyonesids:future[seq[id]] = getids   val everyonesnames:future[seq[future[string]]] = {     everyonesids.map(seq.map(id=>queryname(id)))   }   // i'm trying understand impact of i'll below   everyonesnames.map(seq=>seq.map(fut=>blocking(fut, 1 s))) } queryeveryonesnames

in last line turned future[seq[future[string]]] (notice future within future) future[seq[string]] blocking on inner future.

blocking on future within future feels redundant, @ least here, yet having future within future feels redundant well.

can propose smarter way of getting rid of inner future?

do think blocking on future inside future bad? if why , under circumstances?

yes, future blocking blocking, should avoid that, resources blocked wait result, if in thread.
if understood correctly, question how convert future[seq[future[string]]] future[seq[string]] in non-blocking way.

you can for-comprehensions:

val in =  future[seq[future[string]]] val m = for( <- in ) // seq[future[string]] yield ( future.sequence(a)) // yields m = future[future[seq[string]]] val result = for(a <- m; b <- a) yield (b) // yields future[seq[string]]

edit: or just:

val result = in.flatmap(a => future.sequence(a))

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