IRCTC Tatkal Queue System

Problem

Every Tatkal booking day, 10 lakh people hit the server at 10:00 AM exactly. The database crashes. Nobody gets a ticket.

Solution

Built a Redis queue system that accepts all requests instantly. A worker processes them one by one. Database never sees the spike.

How it works

• POST /book → joins queue, gets position number
• Worker → processes one by one, confirms seats
• GET /status/{id} → check booking result

Tech Stack

• FastAPI, Redis, Python

What I learned

• Why Redis beats Python list (crash persistence)
• Queue based load leveling pattern
• Used by BookMyShow, Razorpay in production