Carlo.jl

Overview

Carlo is a framework that aims to simplify the implementation of high-performance Monte Carlo codes by handling the parallelization, checkpointing and error analysis. What sets it apart is a focus on ease of use and minimalism.

Installation

julia> using Pkg
julia> Pkg.add("Carlo")    Updating registry at `~/.julia/registries/General.toml`
   Resolving package versions...
ERROR: expected package `Carlo [780c37f4]` to be registered

Usage

In order to work with Carlo, a Monte Carlo algorithm has to implement the AbstractMC interface. A full example of this is given in the reference implementation for the Ising model.

Then, to perform simulation, one writes a job script defining all the parameters needed for the simulation, which could look something like the following.

#!/usr/bin/env julia

using Carlo
using Carlo.JobTools
using Ising

tm = TaskMaker()
tm.sweeps = 10000
tm.thermalization = 2000
tm.binsize = 100

tm.Lx = 10
tm.Ly = 10

Ts = range(0.1, 4, length=20)
for T in Ts
    task(tm; T=T)
end

job = JobInfo(@__FILE__, Ising.MC;
    checkpoint_time="30:00",
    run_time="15:00",
    tasks=make_tasks(tm)
)

start(dummy, dummy2) = nothing # hide
start(job, ARGS)

This example starts a simulation for the Ising model on the 10×10 lattice for 20 different temperatures. Using the function start(job::JobInfo, ARGS) enables the Carlo CLI.

The first argument of JobInfo is the prefix for starting the simulation. One possible convention is to use the @__FILE__ macro to automatically start jobs in the same directory as the script file. Alternatively, the script file could be located in a git repository, while the large simulation directory is located elsewhere.

It should be noted that in contrast to some other packages, the parameter files of Carlo are programs. This is especially handy when a calculation consists of many different tasks.