Optimistic concurrency locking in REDIS database

[akumbhare]

Hi,
Have NodeBB used "optimistic concurrency locking"?
I think in NodeBB there is 'UPVOTE' concept,
While upvoting there has to be 'Optimistic concurrency locking',
So it can handle multiple database insert operation at a time while upvoting single post by multiple users.

Please let me know where do I find the code for 'Optimistic Concurrency locking',
and guide me how to handle multiple insert operation at a time in redis database.

Thanks!!