[Python] python: if key not in dictionary add the key. preventing race conditions with...

i am programming a telegram bot where more thread handles every update async. i hard code an empty dictionary and while the bot is running, multiple threads write and read from it.

The most common operation is:

if key not in dict:
dict[key] = value
else:
dict[key].append(another_value)


the problem is that while a thread check if key is or not in dict, and maybe it is not, another thread wrote the key in it.

so basically i have to get rid of this racing condition.

i need a fast solution. searching on the web i found answers talking about threading.Lock(). Those answers are about 10 years old. i wonder if nowadays it's still a good solution or maybe there is some more new library

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