javascriptAsync race conditionHard

System allowing duplicate reservations

Time: 0:00

What it should do

bookSeats(n) handles n concurrent booking requests for a single remaining seat and returns how many bookings succeeded. It should never exceed 1.

What goes wrong

bookSeats(3) returns 3 — three people booked the same single seat. bookSeats(1) correctly returns 1, so the bug only shows up under load.

Hints

This is an async and race conditions bug

A missing await, results in the wrong order, and updates that overwrite each other under load.