Is this a video course?

No. This is an interactive, slide-based learning platform. Each lesson has rich text, animated diagrams, live code editors, and quizzes. You learn by reading, interacting, and doing, not by watching videos passively.

How long do I have access?

Forever. Both pricing tiers are one-time payments with lifetime access. This includes all current 766 lessons and any future content we add.

What level of experience do I need?

None. We start from absolute basics like 'What is latency?' and build up to distributed consensus protocols. The Foundation level assumes zero prior knowledge of system design.

How much does the system design course cost?

7.99 US dollars for lifetime access globally, or 499 Indian rupees for lifetime access in India. One-time payment, no subscription, no hidden fees. 11 lessons are free with no signup required.

What technologies are covered?

Everything from DNS and load balancers to Kubernetes, Kafka, distributed databases, consensus protocols, stream processing, security architecture, and observability. We cover principles and real-world implementations used at Netflix, Google, Amazon, Uber, Stripe, and more.

Is this useful for system design interview preparation?

Yes. The lessons are structured around the exact topics asked in system design interviews at FAANG and top-tier companies. Interactive diagrams help you practice whiteboard-style explanations. Covers everything from URL shortener design to distributed payment systems.

How is this different from ByteByteGo or Educative?

766 interactive lessons (4x more than most competitors), 16 different diagram types that build step by step, real production examples from Netflix, Google, Amazon, Uber, and Stripe, and lifetime access for a one-time payment of $7.99 instead of annual subscriptions costing 100 to 200 dollars per year.

What causes a cache stampede?

A popular cache key expires, and many simultaneous requests all trigger database queries for the same data, A cache stampede (thundering herd) happens when a popular key expires and many concurrent requests all see the cache miss simultaneously. Each request independently queries the database for the same data, multiplying database load by the number of concurrent requests.

In the mutex lock solution, what happens to requests that arrive while one request is already fetching data from the database?

They wait for the lock holder to finish and then read the freshly cached result, With the mutex approach, only one request 'wins' the lock and fetches from the database. All other requests for the same key wait (block) until the lock is released, then read the freshly populated cache entry. This prevents multiple identical database queries but adds latency for the waiting requests.

Why does the probabilistic early expiration (XFetch) approach naturally adapt to traffic volume?

More requests mean more 'dice rolls,' so the chance of at least one early refresh approaches 100% under high traffic, Each request independently decides whether to refresh early based on a random probability. Under high traffic (thousands of requests during the refresh window), the probability that at least one triggers an early refresh is nearly 100%. Under low traffic, fewer dice rolls mean fewer early refreshes, which is fine, because low traffic means a stampede wouldn't be severe anyway.

A CDN serves a page with the header 'Cache-Control: max-age=60, stale-while-revalidate=120'. What happens when a request arrives 90 seconds after the page was cached?

The CDN serves the 90-second-old (stale) response immediately and fetches a fresh copy from the origin in the background, At 90 seconds, the response has exceeded its max-age of 60 seconds but is within the stale-while-revalidate window (60 + 120 = 180 seconds). The CDN serves the stale response immediately (no latency penalty for the user) and triggers a background fetch from the origin to get a fresh copy for subsequent requests.

Cache Stampede Prevention

Name: System Design Masterclass
Availability: InStock

in Caching Strategies

This lesson is part of the full System Design Masterclass. Unlock it along with 765 other lessons for a one-time payment.

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