Suggestion: more verbose output
Show more progress during the scan with time running/remaining and which place is being scanned.
i like the approach of pokeminer (https://github.com/modrzew/pokeminer) - it shows you a minimalistic version of all the running workers:
for each worker you can see a single character indicating its current status, e.g. for logging in an "L" for an error/exception an "E", and when it´s working you just see either a "." or ":".
so when the main script runs you get this output (the whole terminal screen gets refreshed every second)
....:::LL.....:::..::::..::::::LL...LL...E.....:::::.......::....::::. ..::::EEE:....::E:.....:E::::::..............WWW:::....:.....E....E...
without cluttering the whole screen you can see in 2 lines what all your workers are doing!
even more suggestions :-) : a line that outputs starting time, current progress, percentage, time until finished would also be great!
damn, if i would be better at python...