Warning: In serialize(data, node$con, xdr = FALSE) : # 'package:* may not be available when loading

[elgabbas]

I installed future from the GitHub development branch. I receive many warnings for packages terra, tibble, and others when these packages are loaded in the global environment before using future. This happened whether or not both packages are used in the parallel function.

library(future.apply)
plan(multisession, workers = 3)

# magrittr pipe, tibble, and terra are used without warnings
fun1 <- function(x) {
  A <- mtcars %>% head()
  B <- terra::rast()
  c <- tibble::tibble(mtcars)
  list(A, B, C)
}
results <- future_lapply(1:5, fun1, future.seed = TRUE, future.packages = "magrittr")

library(future.apply)
library(tibble)
library(terra)

# Loading tibble and terra in the global environment shows error when working in parallel
plan(multisession, workers = 3)
fun1 <- function(x) {
  A <- mtcars %>% head()
  B <- terra::rast()
  c <- tibble::tibble(mtcars)
  list(A, B, C)
}
results <- future_lapply(
  1:5, fun1, future.seed = TRUE, future.packages = c("magrittr", "tibble", "terra"))
# Warning messages:
#   1: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 2: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 3: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 4: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 5: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 6: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 7: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 8: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 9: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 10: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 11: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 12: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading

library(future.apply)
library(tibble)
library(terra)

# This happened even if both tibble and terra are not used inside future, but when magrittr pipe operator is used
plan(multisession, workers = 3)
fun1 <- function(x) {
  A <- mtcars %>% head()
  A
}
results <- future_lapply(
  1:5, fun1, future.seed = TRUE, future.packages = "magrittr")
# Warning messages:
#   1: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 2: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 3: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 4: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 5: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 6: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 7: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 8: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 9: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 10: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading
# 11: In serialize(data, node$con, xdr = FALSE) :
#   'package:tibble' may not be available when loading
# 12: In serialize(data, node$con, xdr = FALSE) :
#   'package:terra' may not be available when loading

library(future.apply)
library(tibble)
library(terra)

# This shows warnings for terra only!
plan(multisession, workers = 3)
fun1 <- function(x) {
  A <- head(mtcars)
  A
}
results <- future_lapply(1:5, fun1, future.seed = TRUE)

Warning messages:
  1: In serialize(data, node$con, xdr = FALSE) :
  'package:terra' may not be available when loading
2: In serialize(data, node$con, xdr = FALSE) :
  'package:terra' may not be available when loading
3: In serialize(data, node$con, xdr = FALSE) :
  'package:terra' may not be available when loading
4: In serialize(data, node$con, xdr = FALSE) :
  'package:terra' may not be available when loading
5: In serialize(data, node$con, xdr = FALSE) :
  'package:terra' may not be available when loading
6: In serialize(data, node$con, xdr = FALSE) :
  'package:terra' may not be available when loading

[HenrikBengtsson]

Thanks for reporting on this too; I can reproduce this with:

library(future)
library(terra)
plan(multisession, workers = I(1))

f <- future({
  head  ## this is a S4 generic defined by 'terra'
  terra::rast()
}, seed = TRUE)
v <- value(f)

This issue was introduced in future 1.49.0 (2025-05-09), or possibly in globals 1.18.0 (2025-05-08). I'll fix.

[HenrikBengtsson]

This has been fixed in next version of future; please retry:

remotes::install_github("HenrikBengtsson/future", ref = "develop")

[elgabbas]

Thanks @HenrikBengtsson. No warnings appear after updating the package.