DaemonMode and PackageCompiler

DaemonMode and PackageCompiler.jl can be seen as complementary:

PackageCompiler allows users to compile the packages in an image system, so they will not take time to load them by setting the image (with -J parameter).
DaemonMode allows users to load the packages only once, so in next scripts/runs they are already loaded, reducing time in new runs (not the first one).

Each one of them has their own advantages and drawbacks:

PackageCompiler is able to reduce the loading time of the compiled packages, but it takes some time (minutes) to compile them, and it should be done when packages are updated to use the newest versions. Also, reduce greatly the loading time, but for many packages the first execution of functions is not reduced, mainly the loading time.
DaemonMode only can reduce the loading time of one package after that

package was previously used since the Daemon run. It can applies the newest version without delay. It cannot reduce first time, but it can reduce time compiling all functions previously run since last Daemon run (in any program and/or script).

The good news is that both approach can be together applied:

DaemonMode with PackageCompiler

It is simple, you can create a simple compile script like:

# compile.jl
using PackageCompiler
using Pkg

# List of packages to compile (you can custom it)
pkgs = [:StatsBase, :CSV, :DataFrames, :LinearAlgebra, :TimerOutputs, :LoopVectorization, :FLoops, :Tullio, :DataPipes, :Chain]
# Add them
Pkg.add(string.(pkgs))
# Update to last version
Pkg.update()
# Compile to a system file
PackageCompiler.create_sysimage(pkgs; sysimage_path="./ds.jsys")

Then, after compiling: julia compile.jl you will have the packages compiled in an external file ds.jsys. You can decide how frequently you want to update it (I personally use it once every two weeks).

Then, my daemon script for everyday (in bash, for Linux) is javaDSserver (in the same directory as compile.jl):

#!/usr/bin/env bash
# Remove previous daemon
pkill -9 julia
# Run daemon with compiled version, using async and disabling checkbounds
julia -J/mnt/home/daniel/bin/ds.jsys --check-bounds=no -e 'using DaemonMode; serve(async=true)' &

Running the daemon is simple:

$ juliaDSserver

And running a script is:

$ jclient script.jl

In that way, DaemonMode can run faster the script even first time (loading the compiled packages). Also, all packages (compiled or non-compiled) and functions will be run faster after first run.