https://vutg.me/tags/distributed-systems/Recent content in Distributed-Systems on Adam VuHugoenMon, 27 Nov 2023 00:00:00 +0000https://vutg.me/posts/redis-ttl-distributed-lock-for-ticket-reservation/Mon, 27 Nov 2023 00:00:00 +0000https://vutg.me/posts/redis-ttl-distributed-lock-for-ticket-reservation/<p>If you&rsquo;ve ever booked concert tickets or a flight, you&rsquo;ve seen that countdown timer: <em>&ldquo;You have 10 minutes to complete your purchase.&rdquo;</em> That timer isn&rsquo;t just UX theatre — it&rsquo;s a distributed lock with a TTL. This post walks through why that pattern exists and how to implement it with Redis.</p> <h2 id="the-problem-with-naive-ticket-booking"> The problem with naive ticket booking <a class="heading-link" href="#the-problem-with-naive-ticket-booking"> <i class="fa-solid fa-link" aria-hidden="true" title="Link to heading"></i> <span class="sr-only">Link to heading</span> </a> </h2> <p>The simplest correct implementation of a booking system uses a database transaction:</p>