D10Locks and double booking

The problem

1 s on screen = 100 ms

Two people click “buy” on the same seat at once. Who gets it?

Read the seat, then book it

A booking reads its seat and writes it only if it was free. Shoppers spread over 2,000 seats, until the sale opens.

Live metrics for each version of the scene
Metric	Read, write	A guard	Change
	0	0	—
	—	—	—
target ≤ 400 ms	—	—	—

D10Locks and double booking

Two people click “buy” on the last seat at the same moment. Without a lock, both succeed.