CODEWITHSUNDEEP
r
eartoolbox
eartoolbox

Reputation: 367

Why does this promise cause blocking in R?

In the following, I do not understand why the code blocks. I am expecting that printing "boom" should happen straight away, before printing "after Sys.sleep". I thought everything inside the future_promise expression should not cause blocking. What am I misunderstanding?

library(promises)

test <- function() {
  promise <- future_promise({
    Sys.sleep(10)
    print("after Sys.sleep")
  })
  print("boom")
}

test()

Ok, this does what I was after!:

library(promises)
plan(multiprocess)

test2 <- function() {
  future({
    # expensive operations go here...
    Sys.sleep(10)
  }) %...>% (function(result) {
    print("after Sys.sleep")
  })
  print("boom")

}

test2()

Upvotes: 2

Views: 124

Answers (1)

eartoolbox
eartoolbox

Reputation: 367

This does what I was expecting:

library(promises)
plan(multiprocess)

test2 <- function() {
  future({
    Sys.sleep(10)
  }) %...>% (function(result) {
    print("after Sys.sleep")
  })
  print("boom")

}

test2()

Upvotes: 1

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