getExpression(future, ...)
options(mc.cores=0L)
, which
means that no additional R processes may be spawned off
by functions such as mclapply()
and friends (*).Currently it is not possible to specify what type of nested futures to be used, meaning the above default will always be used. See https://github.com/HenrikBengtsson/future/issues/37 for plans on adding support for custom nested future types.
(*) Note that using mc.cores=0
will unfortunately cause
mclapply()
and friends to generate an error saying
"'mc.cores' must be >= 1". Ideally those functions should
fall back to using the non-multicore alternative in this
case, e.g. mclapply(...)
=> lapply(...)
.
See https://github.com/HenrikBengtsson/Wishlist-for-R/issues/7
for a discussion on this.