Mobility

“Civilization, Modernization, Value Investing, and China” is a book by the renowned value investor Mr. Lu Li. It discusses the development of civilization, the emergence of modernization, and value investing, and explores these topics in the context of China’s actual situation. I personally feel this is an extremely valuable book worth reading repeatedly. It is of great help in understanding the logic of how this world operates and in building correct investment philosophy. As the title sug...

The book I’m discussing today, “I Walked on the Edge of Breakdown: Yu Minhong’s Personal Account of New Oriental’s Entrepreneurial Development,” is an autobiographical work by Mr. Yu Minhong, recounting his many experiences and psychological journey since founding New Oriental. Today, I’ll summarize the content of this book and share my personal reflections. The book begins before Yu Minhong founded New Oriental. Yu Minhong was originally a teacher at Peking University, and he left the univ...

(I recently reorganized this article. Welcome to read the latest version: https://lichuanyang.top/posts/45718/) This article is translated from https://martinfowler.com/articles/patterns-of-distributed-systems/. The original author summarizes various distributed systems used in enterprise architectures, extracting common “patterns.” As the first article in this series, it introduces the characteristics of distributed systems and some common issues. I highly recommend reading this article and ...

In the previous article, we introduced the low-level data structures defined in Redis. Next, in this article, we will combine these with the objects provided by Redis to see how these data structures are used in practice. Redis primarily includes the following objects: strings, lists, hashes, sets, sorted sets, HyperLogLog, GEO, etc. This article will mainly cover how these objects are implemented. For their commands, you can refer to the official Redis documentation, which provides detaile...

Redis, as a widely used in-memory database, has made many extreme optimizations at the code level to achieve better performance. An important part of this is the use of underlying data structures. Redis optimizes the usage of different structures based on data volume, data size, and other factors, thereby achieving better operational efficiency and memory usage. Redis’s core data structures include Simple Dynamic Strings, linked lists, dictionaries, skip lists, integer sets, and compressed li...

As everyone knows, design patterns are an extremely important discipline for programmers. However, because design patterns cover such a broad scope and involve many abstract concepts, they can be quite difficult to master. The best way to learn design patterns is to combine them with practical experience. Every time you work on a requirement — especially complex ones, or when you detect signs of smelly code — you can flip through the design patterns to see which ones might apply. Therefore, I...

Over the years of working, I’ve been constantly thinking about what a programmer actually does. As I’ve gained more experience, my understanding has continuously evolved. Writing this article now serves two purposes: sharing my thoughts, and leaving a record to revisit in a couple of years to see how my understanding has further changed. The Essence of Programming as a CareerI want to discuss this from two perspectives. First, from the work itself — in my view, a programmer’s work falls int...

As is well known, using batch operations with MySQL can significantly improve performance when dealing with large datasets. However, when using MySQL in Java, certain details must be carefully handled; otherwise, batch operations may not actually take effect, and you won’t benefit from the performance gains of batching. The ProblemRecently, I noticed that the performance profile of a particular SQL query was abnormally slow — inserting several thousand records in batch was taking on the ord...

A while ago, when I was trying to improve the unit tests for a project, I realized that I never had a particularly clear understanding of how to write unit tests. So I looked up some materials, and in the process discovered that everyone’s perspectives are quite different. Every article I read updated my own understanding. This article combines others’ viewpoints with my own practical experience to summarize what I currently believe to be correct. It probably won’t be the most definitive answ...

RocketMQ’s MessageQueue has a unique design: it splits a queue into readQueueNums (read queue count) and writeQueueNums (write queue count). In the vast majority of cases, these two values must be equal — if they diverge, serious problems arise. So why separate them? The answer lies in smooth scaling. What is a MessageQueue?In RocketMQ, a Topic is a logical category for messages, while a MessageQueue is the physical shard of a Topic, similar to Kafka’s Partition. A key constraint: the numbe...