Basic question about thread interaction

General Usage
,
1

Hi everyone. I’m trying to learn how to use threads in Julia by comparing them to the Python examples from Ramalho’s Fluent Python book Fluent Python, 2nd Edition [Book].

The basic Python example is:

import itertools
import time
from threading import Thread, Event

def spin(msg: str, done: Event) -> None:
    for char in itertools.cycle(r'\|/-'):
        status = f'\r{char} {msg}'
        print(status, end='', flush=True)
        # returns False after s and keep looping
        # or if another treat calls Event.set(), return True and break loop
        if done.wait(.1):
            break
    blanks = ' ' * len(status)
    print(f'\r{blanks}\r', end='')

def slow() -> int:
    # blocks main thread, but releases GIL, so other threads can run
    time.sleep(3)
    # long function finishes
    return 42

def supervisor() -> int:
    done = Event() # starts as False
    spinner = Thread(target=spin, args=('thinking!', done))
    print(f'spinner object: {spinner}')
    spinner.start() # start spin thread
    result = slow() # blocks main thread
    done.set() # spin loop will end
    spinner.join() # wait for spin thread to end
    return result

supervisor()

I have a Julia implementation as (started Julia with 4 threads):

using Base.Threads

function spin(msg::String, done::Threads.Atomic{Bool})
    for char in Iterators.cycle("\\|/-")
        status = "\r$(char) $(msg)"
        print(status)
        flush(stdout)
        sleep(0.1)
        if done[]
            break
        end
    end
    blanks = " " ^ (length(msg)+3)
    print("\r$(blanks)\r")
end

function slow()
    sleep(3)
    return 42
end

function supervisor()
    done = Threads.Atomic{Bool}(false);
    spinner = Threads.@spawn spin("thinking!", done)
    println("spinner object: $(spinner)")
    result = slow()
    done[] = true
    wait(spinner)
    return result
end

supervisor()

My question is twofold. First is this an idiomatic or Julian way to use Threads.Atomic? Secondly, could someone suggest how to accomplish this with Event or Condition? I found the documentation for those 2 types hard to follow. Thanks everyone.