The Easiest Concurrency Problem - Race Condition

Drawing from my own experience of feeling despondent when trying to implement practical code during my first MSA transition—despite knowing the theory—I will help you grow into a developer who guarantees perfect data consistency amidst any system failure by directly rolling back daunting compensation logic through 9-step practical patterns and AI Agent coding.

Many backend developers use Redis, but in reality, they often use it merely as a simple cache server. There are many cases where developers know the Redis data types but don't know how to apply them in practice, lack experience implementing real-world patterns like distributed locks or rate limiting, or fail to understand Redis from a backend architecture perspective. I also had the experience of pondering how to utilize Redis in a high-traffic environment while developing actual services. This is because knowing simple commands is entirely different from solving service problems with Redis. This course starts with the basic concepts and data structures of Redis and progresses through learning by implementing core patterns used in actual backend services step-by-step. In particular, you will learn how to solve the following practical problems using Redis: Caching (Cache-Aside) strategies to reduce server load, Distributed Sessions (Session Store) to share login states, Distributed Locks to solve concurrency issues, Rate Limiting to prevent API overload, and Real-time Ranking Systems (Leaderboards) for large-scale users. All hands-on exercises are conducted in a real API server environment based on Python FastAPI. Rather than just learning simple CLI commands, you will understand how Redis is used in backend systems by implementing it yourself. Through this course, you will be able to utilize Redis not just as a simple cache, but as a core tool for designing backend architecture.

This course is for developers who want to find fundamental solutions in environments where response times slow down as traffic increases, thread pools are quickly exhausted, and bottlenecks worsen with more external API calls. It helps you look at problems from the perspective of changing the architecture itself, rather than simply scaling out servers. Through this course, you will first understand the limitations of the traditional Spring MVC "Thread per Request" model. You will examine at the code level why throughput doesn't increase even when CPU resources are available, and exactly how blocking I/O occupies system resources. Next, you will learn the concepts and standard specifications of Reactive Streams and master how to handle data streams using Reactor's Mono and Flux. Beyond simple usage, you will learn through hands-on practice how data flows start, how they are consumed, and how throughput is controlled. In particular, you will directly implement design patterns that prevent OOM (Out of Memory) or overloads using Back Pressure. Additionally, you will understand the event loop-based processing structure of Spring WebFlux and conduct comparative exercises on how Non-Blocking I/O operates during actual request processing. By placing MVC and WebFlux side-by-side to verify their structural differences, you will also establish criteria for when to choose Reactive. This goes beyond simply "learning asynchrony." You will learn how to handle more requests with fewer threads, how to maintain a stable flow in environments with high external API dependencies, and develop the design intuition to secure throughput in high-concurrency environments.

This course goes beyond basic CRUD-level database usage, helping you develop the PostgreSQL skills needed in the AI era from a practical, real-world perspective. Drawing on AI development experience in Silicon Valley, you’ll gradually learn how to design and use JSON, indexes, transactions, and pgvector in actual services, while gaining the skills to solve complex data structure and performance problems.

This course provides a step-by-step learning path, ranging from the fundamental usage of MySQL to advanced techniques required in real-world production environments. It covers a wide range of topics, including data modeling techniques based on various case studies and practical data, evaluating the effectiveness of Foreign Key designs, analyzing Google Calendar schema DDL, and modern DDL design principles. Through this course, you will gain an in-depth understanding of how to utilize MySQL as a core system component rather than just a simple database.

This course covers everything from building a database and creating tables to manipulating and modifying data within the database using various SQL queries.

Have you ever felt frustrated with table design? This course is for those who have had concerns like, "Is this table right?", "Which column should be the PK?", "Is it okay to connect relationships this way?", or "Will I have to rebuild the table when adding new features?"

The most definitive practical guide for developers who want to integrate AI into their Spring projects right away! Beyond simple LLM API calls, you will perfectly master building production-level AI environments that can be immediately applied to real business logic using RAG and MCP.

At some point in backend development, you start to have these concerns. It's that moment when services expand and traffic increases, and you begin to feel the limitations of simple REST communication and CRUD structures. I experienced these same issues in the field and went through much trial and error balancing performance and structural complexity. The solution I chose during that process was NATS. Its simple configuration based on a single binary, ultra-low latency performance in microseconds, and the fact that it provides essential features—from Pub/Sub to Queue Groups and JetStream—without being overkill made it a very practical choice for real-world service environments. This course is not just a list of NATS features. Based on the problems I faced in practice, I explain through code and workflows why I chose NATS in certain situations and how I designed the architecture. This course is designed to help everyone—from those new to messaging systems to backend developers preparing for employment and senior developers considering better architectures—understand distributed systems and grow to the next level.

This course focuses more on data modeling through entity design than on JPA technical explanations. Based on the principle that solid DB design is the foundation of application development, we analyze various design patterns—such as one-to-many, many-to-many, inheritance, and collections—alongside business scenarios. You will learn by directly observing the process of code being transformed into actual tables on screen. To ensure immediate practical application, we provide business use cases, source code, and test codes for each design pattern.

Channel Talk interviewers will directly analyze the difference between failing and passing answers to the same questions, and help you prepare for actual follow-up questions.

The most definitive practical guide for job seekers and junior developers new to CI/CD automation! You will perfectly master everything from building CI/CD pipelines using Jenkins to creating production-level automated deployment environments integrated with AWS infrastructure (S3, ECS).

By implementing various practical data analysis cases using SQL, you can simultaneously improve your data analysis and SQL utilization skills.

This course teaches you how to build a practical Unity game with a database. It covers difficult-to-access topics in an easy-to-follow lecture format.

Developing an AI Safety Report Service with React + Spring AI The 5th Neo + Essential project lecture is about building a Safety Report system, an idea for improving government systems!

This is a course for learning MS-SQL through baseball and corporate databases.

This is a Docker guide for beginners who don't know anything about Docker. We focused on helping you quickly learn why Docker is popular and how to use it, without getting into complicated details.

This is a Kubernetes guide for beginners who don't know anything about Kubernetes. It is written in a way that even beginners can understand.

Learn how to analyze 5 million records of Korean apartment transaction data using PostgreSQL. It covers the process of deriving meaningful insights through data cleaning, transformation, and various SQL queries.

Learn from the beginning how to set up a development environment that even an ordinary office worker can easily understand. It is practice-oriented and focuses on students learning various development tools such as Vim, VS Code, Git, Docker, and remote development. You can learn how to build an efficient development environment by learning step-by-step from the basic usage of each development tool to advanced functions.

This is a full-stack hands-on course where you will implement a ChatGPT clone from scratch. From Spring Boot server to React frontend | Neo + Essential This is not just a course where you simply follow along with the code; it guides you through actual service deployment so you can build a high-quality AI chatbot service.