A dirty hack to make tqdm process safe http://daily.belltail.jp/?p=2389

process_safe_tqdm.py

import tqdm
import multiprocessing

class ProcessSafeTqdm(tqdm.tqdm):
    def __init__(self, *args):
        super(ProcessSafeTqdm, self).__init__(*args)
        self.correct_count = multiprocessing.Value('i', 0)

    def update(self, n=1):
        with self.correct_count.get_lock():
            self.n = self.correct_count.value
            super(ProcessSafeTqdm, self).update(n)
            self.correct_count.value += n

    def close(self):
        self.n = self.correct_count.value
        super(ProcessSafeTqdm, self).close()

usage.py

import sys
import time
import tqdm
import multiprocessing
from process_safe_tqdm import ProcessSafeTqdm

def worker(pbar):
    pbar.update()

ar = list(range(100))
#with tqdm.tqdm(ar) as pbar:    # It doesn't produce meaningful progress bar
with ProcessSafeTqdm(ar) as pbar:
    jobs = []
    for t in ar:
        job = multiprocessing.Process(target=worker, args=(pbar,))
        job.start()
        jobs.append(job)
    for job in jobs:
        job.join()