`num_workers` doesn't seem to work as intended

I use --num_workers 12 but htop still shows only two cores with 100% utilization. I'm not sure why though as

Line 124 in e9c1419

with multiprocessing.Pool(num_workers, maxtasksperchild=10) as p:

seems to be right 🤔

Hi, sorry for the late reply. I didn't watch this repo until now...

Could you tell me which dataset you are converting? I can not reproduce this issue. Thank you!