[BUG] a function is not found in the env when I use the parallel package

[DevIA05]

Describe the bug
I have two functions myfunct1 and myfunct2. myfunct1 uses the myfunct2 function. I want to use these two functions in a foreach()%dopar%{} loop but i get a error:

Error in {: task 1 failed - "unable to find function 'myfunct2'"

To Reproduce
I create util and funct files with this commands:

golem::add_fct("function", with_test = F)
golem::add_utils("util", with_test = F)

utils.util.R

myfunct1 <- function(){ return(myfunct2()) }
myfunct2 <- function(){ return(matrix(c("1", "2"), nrow = 1)) }

ftc_function.R

#' @importFrom parallel makeCluster
#' @importFrom parallel stopCluster
#' @importFrom parallel detectCores
#' @importFrom doParallel registerDoParallel
#' @importFrom foreach %dopar%
#' @importFrom foreach foreach
rbinddf <- function(){
  num_cores <- detectCores()
  cl <- makeCluster(num_cores)
  print(getwd())
  registerDoParallel(cl)
  df <- foreach(i = 1:5, .combine = 'rbind',
                .packages = c(),
                .export = c("myfunct1", "myfunct2")) %dopar% {
                  return(myfunct1())
                }
  stopCluster(cl)
  env <- foreach:::.foreachGlobals
  rm(list=ls(name=env), pos=env)
  return(df)
}

app_server.R

app_server <- function(input, output, session) {
  print(rbinddf())
}

session info

> devtools::session_info()
─ Session info ────────────────────────────────────────────────────────────────────────
 setting  value
 version  R version 4.2.3 (2023-03-15 ucrt)
 os       Windows 10 x64 (build 19045)
 system   x86_64, mingw32
 ui       RStudio
 language (EN)
 collate  French_France.utf8
 ctype    French_France.utf8
 tz       Indian/Mauritius
 date     2024-02-22
 rstudio  2023.03.0+386 Cherry Blossom (desktop)
 pandoc   NA

─ Packages ────────────────────────────────────────────────────────────────────────────
 ! package        * version    date (UTC) lib source
   attachment       0.4.0      2023-05-31 [1] CRAN (R 4.2.3)
   attempt          0.3.1      2020-05-03 [1] CRAN (R 4.2.3)
   brio             1.1.3      2021-11-30 [1] CRAN (R 4.2.3)
   bslib            0.5.1      2023-08-11 [1] CRAN (R 4.2.3)
   cachem           1.0.8      2023-05-01 [1] CRAN (R 4.2.3)
   callr            3.7.3      2022-11-02 [1] CRAN (R 4.2.3)
   cli              3.6.1      2023-03-23 [1] CRAN (R 4.2.3)
   codetools        0.2-19     2023-02-01 [2] CRAN (R 4.2.3)
   colorspace       2.1-0      2023-01-23 [1] CRAN (R 4.2.3)
   config           0.3.2      2023-08-30 [1] CRAN (R 4.2.3)
   crayon           1.5.2      2022-09-29 [1] CRAN (R 4.2.3)
   desc             1.4.2      2022-09-08 [1] CRAN (R 4.2.3)
   devtools         2.4.5      2022-10-11 [1] CRAN (R 4.2.3)
   digest           0.6.33     2023-07-07 [1] CRAN (R 4.2.3)
   doParallel       1.0.17     2022-02-07 [1] CRAN (R 4.2.3)
   dplyr            1.1.2      2023-04-20 [1] CRAN (R 4.2.3)
   DT               0.31       2023-12-09 [1] CRAN (R 4.2.3)
   ellipsis         0.3.2      2021-04-29 [1] CRAN (R 4.2.3)
   fansi            1.0.4      2023-01-22 [1] CRAN (R 4.2.3)
   fastmap          1.1.1      2023-02-24 [1] CRAN (R 4.2.3)
   fontawesome      0.5.2      2023-08-19 [1] CRAN (R 4.2.3)
   foreach          1.5.2      2022-02-02 [1] CRAN (R 4.2.3)
   fs               1.6.3      2023-07-20 [1] CRAN (R 4.2.3)
   generics         0.1.3      2022-07-05 [1] CRAN (R 4.2.3)
   ggplot2          3.4.4      2023-10-12 [1] CRAN (R 4.2.3)
   glue             1.6.2      2022-02-24 [1] CRAN (R 4.2.3)
   golem            0.4.1      2023-06-05 [1] CRAN (R 4.2.3)
   gtable           0.3.4      2023-08-21 [1] CRAN (R 4.2.3)
   htmltools        0.5.6      2023-08-10 [1] CRAN (R 4.2.3)
   htmlwidgets      1.6.2      2023-03-17 [1] CRAN (R 4.2.3)
   httpuv           1.6.11     2023-05-11 [1] CRAN (R 4.2.3)
   iterators        1.0.14     2022-02-05 [1] CRAN (R 4.2.3)
   jquerylib        0.1.4      2021-04-26 [1] CRAN (R 4.2.3)
   jsonlite         1.8.4      2022-12-06 [1] CRAN (R 4.2.3)
   knitr            1.44       2023-09-11 [1] CRAN (R 4.2.3)
   later            1.3.1      2023-05-02 [1] CRAN (R 4.2.3)
   lifecycle        1.0.3      2022-10-07 [1] CRAN (R 4.2.3)
   magrittr         2.0.3      2022-03-30 [1] CRAN (R 4.2.3)
   memoise          2.0.1      2021-11-26 [1] CRAN (R 4.2.3)
   mime             0.12       2021-09-28 [1] CRAN (R 4.2.0)
   miniUI           0.1.1.1    2018-05-18 [1] CRAN (R 4.2.3)
   munsell          0.5.0      2018-06-12 [1] CRAN (R 4.2.3)
   pillar           1.9.0      2023-03-22 [1] CRAN (R 4.2.3)
   pkgbuild         1.4.2      2023-06-26 [1] CRAN (R 4.2.3)
   pkgconfig        2.0.3      2019-09-22 [1] CRAN (R 4.2.3)
   pkgload          1.3.3      2023-09-22 [1] CRAN (R 4.2.3)
   prettyunits      1.2.0      2023-09-24 [1] CRAN (R 4.2.3)
   processx         3.8.2      2023-06-30 [1] CRAN (R 4.2.3)
   profvis          0.3.8      2023-05-02 [1] CRAN (R 4.2.3)
   promises         1.2.1      2023-08-10 [1] CRAN (R 4.2.3)
   ps               1.7.5      2023-04-18 [1] CRAN (R 4.2.3)
   purrr            1.0.2      2023-08-10 [1] CRAN (R 4.2.3)
   R6               2.5.1      2021-08-19 [1] CRAN (R 4.2.3)
   Rcpp             1.0.10     2023-01-22 [1] CRAN (R 4.2.3)
   remotes          2.4.2.1    2023-07-18 [1] CRAN (R 4.2.3)
   rlang            1.1.1      2023-04-28 [1] CRAN (R 4.2.3)
   roxygen2         7.2.3      2022-12-08 [1] CRAN (R 4.2.3)
   rprojroot        2.0.3      2022-04-02 [1] CRAN (R 4.2.3)
   rsconnect        1.1.0      2023-09-05 [1] CRAN (R 4.2.3)
   rstudioapi       0.15.0     2023-07-07 [1] CRAN (R 4.2.3)
   sass             0.4.7      2023-07-15 [1] CRAN (R 4.2.3)
   scales           1.3.0      2023-11-28 [1] CRAN (R 4.2.3)
   sessioninfo      1.2.2      2021-12-06 [1] CRAN (R 4.2.3)
   shiny          * 1.7.5      2023-08-12 [1] CRAN (R 4.2.3)
   shinydashboard   0.7.2      2021-09-30 [1] CRAN (R 4.2.3)
   shinymaterial    1.2.0      2020-08-31 [1] CRAN (R 4.2.3)
   stringi          1.7.12     2023-01-11 [1] CRAN (R 4.2.2)
   stringr          1.5.0      2022-12-02 [1] CRAN (R 4.2.3)
 R testgolem      * 0.0.0.9000 <NA>       [?] <NA>
   testthat         3.1.10     2023-07-06 [1] CRAN (R 4.2.3)
   tibble           3.2.1      2023-03-20 [1] CRAN (R 4.2.3)
   tidyselect       1.2.0      2022-10-10 [1] CRAN (R 4.2.3)
   urlchecker       1.0.1      2021-11-30 [1] CRAN (R 4.2.3)
   usethis          2.2.2      2023-07-06 [1] CRAN (R 4.2.3)
   utf8             1.2.3      2023-01-31 [1] CRAN (R 4.2.3)
   vctrs            0.6.3      2023-06-14 [1] CRAN (R 4.2.3)
   withr            2.5.0      2022-03-03 [1] CRAN (R 4.2.3)
   xfun             0.40       2023-08-09 [1] CRAN (R 4.2.3)
   xml2             1.3.3      2021-11-30 [1] CRAN (R 4.2.3)
   xtable           1.8-4      2019-04-21 [1] CRAN (R 4.2.3)
   yaml             2.3.7      2023-01-23 [1] CRAN (R 4.2.3)

 [1] C:/Users/user/AppData/Local/R/win-library/4.2
 [2] C:/Program Files/R/R-4.2.3/library

 R ── Package was removed from disk.

[VincentGuyader]

Thank you for this interesting bug report. It's not so much an issue specific to golem itself, but rather about how to create a function that uses foreach in a package.

My initial attempt was to ensure that the functions myfunct1 and myfunct2 were properly exported. By adding the appropriate @export tags, it works much better:

#' @export

myfunct1 <- function(){
  return(myfunct2()) }


#' @export
myfunct2 <- function(){
  return(matrix(c("1", "2"), nrow = 1)) }

then : attachment::att_amend_desc()

remotes::install_local()

yourapp::rbinddf()

[DevIA05]

Hello, thank for your help.
I tried this too: instead of having the value of myfunct2 directly in the myfunct1 function I passed it as an argument to the function

myfunct1 <- function(val2){ return(val2)) }

rbinddf <- function(){
     ...
     df <- foreach(...) %dopar% {
                  val2 <- myfunct2()
                  val1 <- myfunct1(val2)
                  return(val1)
}