simple_fork_join.py

#!/usr/bin/env python3

import threading
import multiprocessing


def fork_join(jobs, results, runner, cores=None):
    class SimpleCtrl:
        def __init__(self):
            self.aborted=False

    def thread_main(jobs, results, runner, ctrl):
        while jobs:
            job = jobs.pop(0)
            result = runner(job)
            if ctrl.aborted:
                break
            results.append(result)

    if not cores:
        cores = multiprocessing.cpu_count()
    
    ctrl = SimpleCtrl()

    try:
        threads = []
        for i in range(0, cores):
            thread = threading.Thread(target=thread_main,args=(jobs,results,runner,ctrl))
            thread.daemon = True
            thread.start()
            threads.append(thread)
        for thread in threads:
            thread.join()
    except BaseException as e:
        ctrl.aborted=True
        raise e

# ------------------------------------------

import subprocess
import random

jobs = []
for i in range(0, 100):
    jobs.append((random.random()*10.0 + 5.0, i))

results = []
try:
    def thread(job):
        time, i = job
        subprocess.run(f"sleep {time}; echo thread {i:03} slept {time:.2f}", shell=True)
        return i
        
    fork_join(jobs, results, thread)
except KeyboardInterrupt as e:
    print("abort")

print("---")
last = [0, 0]
for i in sorted(results):
    if i == last[1] + 1:
        last[1] += 1
    else:
        print(last)
        last = [i, i]
print(last)