Glos locking

Locking Strategies

These are stategies to handle contention for resources.

There are two general models to deal with these situations that you can observe in the wild:

1. Pessimistic. You take a time-bombed lock on an object and reserve it for the client. Ticketmaster operates their web site that way. When they show you a set of seats tickets they are yours until the clock ticks down.
2. Optimistic. There's no lock. Expedia/Orbitz work that way. When they show you a seat, you don't get it until you book it and there is no promise made.

That said, 1 isn't the only way travel agents work. You can absolutely call your airline and ask them to do 1 for you and they'll give you 24h (or longer with status) to consider whether you actually want the ticket.

_All expected state transitions in these two models are not failures, meaning that if you try to book a seat in model 2 and someone beats you to it, that's just a normal outcome of the optimistic strategy.

• Clemens Vasters_