How to run multiple threads properly

[cyberion1985]

okay, so after some time adopting the above approach, I can finally reply.

This doesn't work :

_=[threading.Thread(target=csv2xlsx, args=(file_name,)).start()forfile_nameinfiles_list]

It might work as 

    for file_name in CSVFILES:
        threading.Thread(target=MAIN_CSV, args=(file_name,)).start()

...which I will go and test now :

main_INIT.py (main init and core script - will run the below scripts as threads)
main_process_PDF.py
main_process_CSV.py (processes the CSV files simultaneously with threads) 

So in essence :

#this is main_INIT.py
#do something

#run function from main_process_PDF.py
#run function from main_process_CSV.py
#is function from main_process_PDF.py done ? is function from main_process_CSV.py done ? If both = yes, continue, else = wait .

#do something

This doesn't work. In both cases, running it alone or inside a function, the CSV processes will not wait until all are done. They will simply run over to the next part of the script. 

---

...then I also tried

[python]
    for file_name in CSVFILES:
        threading.Thread(target=MAIN_CSV, args=(file_name,)).start()
        threading.Thread(target=MAIN_CSV, args=(file_name,)).join()
[python/]