use_julia: Start Julia and activate environment

Description

Start Julia session and activate Julia environment to simulate stock-and-flow models. To do so, Julia needs to be installed (see https://julialang.org/install/) and findable from within R. See this vignette for guidance. In addition, the Julia environment specifically for sdbuildR needs to have been instantiated. This can be set up with install_julia_env().

Usage

use_julia(stop = FALSE, restart = FALSE, nthreads = NULL)

Value

Returns NULL invisibly, used for side effects

Arguments

stop: If TRUE, stop active Julia session. Defaults to FALSE.
restart: If TRUE, force Julia session to restart.
nthreads: If not NULL, set the number of threads for Julia to use. This will temporarily set the environment variable JULIA_NUM_THREADS and restart Julia if it is already running to apply the new thread setting. See this page for more details on threading in Julia.

Details

In every R session, use_julia() needs to be run once (which is done automatically in simulate()), which can take around 30-60 seconds.

Examples

Run this code

if (FALSE) { # Sys.getenv("NOT_CRAN") == "true"
# Start a Julia session and activate the Julia environment for sdbuildR
use_julia()

# Start Julia with 2 threads (only works if threading is supported)
use_julia(nthreads = 2)

# Restart Julia session (in case of issues)
use_julia(restart = TRUE)

# Stop Julia session
use_julia(stop = TRUE)
}