System Design for Interviews and Beyond (short summary)

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Detailed course review

An article with a detailed overview of the System Design for Interviews and Beyond course

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System Design for Interviews and Beyond

Authors: LeetCode Team
Publisher: LeetCode
Length: online course

Detailed analysis of the Leetcode course: from system requirements to practical design problems.

Original

Why this course?

There is a lot of theory in this course, but it is presented in practice-oriented form — the author does not talk about conditional networks from the beginning of time to the present day, but reveals the basic concepts when it comes to communication between system components.

A similar thing happens with data storage - it’s easy to go deep into theory, but it’s difficult to resist talking about B-Tree and LSM-Tree along the way, considering the real challenges of system design. But the author copes well with this challenge and tells it both clearly and quite accurately.

Now let's go through the content of the course and look at each section in more detail.

Course content

The course covers all key aspects of system design - from basic requirements to specific example solutions. Let's look at each section in more detail.

1. Determine system requirements

The course starts with the most important thing - how to correctly determine the requirements. The author talks about the importance of separation functional And non-functional requirements, and then goes through typical architectural characteristics (-ilities) that are usually dealt with in system design interviews:

• High availability — the system is available and working
• Fault tolerance — the system experiences component failures
• Scalability — the system copes with increasing load
• Performance — the system responds quickly
• Durability — no data is lost
• Consistency — data is consistent between components
• Maintainability — the system is easy to develop and maintain
• Security — the system is protected from threats
• Cost efficiency — the system does not ruin the company

2. Achieving system qualities through infrastructure

The author smoothly moves from theoretical requirements to practice - how these characteristics are achieved at the level of system deployment. The concepts covered here are:

• Regions and availability zones
• Data centers and racks
• Servers, virtual machines, containers
• Serverless - when you don’t want to think about servers

I believe that this base need to knowto design coherent systems. Understanding the infrastructure layers helps you make informed decisions about replication, fault tolerance, and latency.

3. Fundamentals of reliable, scalable and fast communications

In order for individual parts to form a system, these parts must be able to communicate effectively with each other. This is one of the key sections of the course, and the author goes into detail:

• Synchronous and asynchronous communications — when we expect an answer and when we don’t
• Asynchronous Communication Patterns — messaging queue, publish/subscribe, competing consumers, request/response, priority queue, claim check
• Network protocols — UDP, TCP/IP, HTTP and their trade-offs
• Blocking and non-blocking I/O — how not to block the entire server with one request
• Data encoding formats — text vs binary, how to fumble the data scheme, backward/forward compatibility

4. Caching to improve performance

5. Queues in distributed systems

This is one of my favorite sections of the course. The author examines in detail queues and their use in distributed systems - and in system design you usually design a distributed system.

• Bounded and unbounded queue — and also circular buffer
• Queue overflow — load shedding, rate limiting, dead letter queues, backpressure, elastic scaling
• Producer-consumer pattern — blocking queues, semaphores
• Thread pools — difference between CPU-bound and I/O-bound tasks, graceful shutdown
• Batching — and parallel processing jobs for efficiency

6. Data storage device

Let's move on to one of the most important topics - how data storage works from the inside. The author examines the topic quite deeply, but without unnecessary academicism:

7-10. Data delivery: reliable, fast, at scale

The next four sections cover how to deliver data between system components. The author examines three key aspects: reliability, speed and scale.

These three aspects often conflict with each other, and the author does a good job of showing the trade-offs between them.

11-12. Protecting clients and servers

The last theoretical sections are devoted to fault tolerance patterns - how to protect a system from cascading failures and isolate problems:

• Circuit Breaker — a fuse that opens the circuit in case of problems and prevents cascading failures from spreading
• Bulkhead — isolating system components from each other so that a problem in one place does not affect the rest
• Shuffle Sharding — load distribution to minimize blast radius during failures

13. Practical examples

The course concludes with practical design problems. This is a great way to apply all the concepts you've learned with real-life examples:

Conclusion

In the following chapters we will look at other sources on System Design and compare their approaches.