What do you think is the best way to manage concurrency in this (made up) scenario?
1) You are selling Orders for items of various ProductVariants, belonging to one Product 2) There may be an upper limit to how many Orders you can take for any given Product 3) For our example today, you can only accept three more orders for any combination of ProductVariants of a Product 4) Two users put in three Orders, at the same time It's in the realm of millisecond possibility, then, for this to happen: Person 1: Validate that 3 Orders can be made for Product 123 => true Person 2: Validate that 3 Orders can be made for Product 123 => true Person 1: Orders.create(:product_variant => 9); Orders.create (:product_variant => 8); Orders.create(:product_variant => 7) Person 2: Orders.create(:product_variant => 6); Orders.create (:product_variant => 5); Orders.create(:product_variant => 4) Oops! 6 Orders placed! What do you think is the best way to prevent overselling in this case? I've considered: * Table locking (sucks) * Setting a lock file per-Product (filesystem-y and not elegantly scalable past one machine) * Setting a lock variable per-Product in a memcached store * A single-worker queue that validates and processes orders in sequence * A per Product single-worker queue that validates and processes orders in sequence * Something I haven't considered? What do you think? Steve! --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk@googlegroups.com To unsubscribe from this group, send email to rubyonrails-talk+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
