Are advisory locks guaranteed to be First Come First Serve? And can the behavior be relied upon? - Mailing list pgsql-general

I was playing with Advisory locks. I opened three connections to the database And obtained a lock with the same key. I noticed that the locks were obtained in the order of requests. I was wondering whether the locks are guaranteed to be First Come First Serve and can this behaviour be relied upon.

I read the docs here. But it didn't mention anything.

Thanks a lot for your time and efforts