00 Java Performance Optimization Is the Alchemist's Stone for Senior Architects

00 Java Performance Optimization is the Alchemist’s Stone for Senior Architects #

Hello, I’m Li Guo. As the author of the course “Java Performance Optimization and Interview Questions in 21 Lessons,” let me briefly introduce myself.

I used to work as a senior architect at JD Financial and Momo Technology. During my tenure, I had extensive experience in optimizing low-level middleware and operating systems, involving a lot of tuning work in high-concurrency scenarios, such as cache optimization, multi-threading optimization, and JVM tuning. Therefore, I have accumulated rich practical experience in performance optimization under high-concurrency conditions, as well as my own set of optimization ideas and techniques. I have optimized a slow-running complex business, increasing its single-machine QPS from 2k/s to 20k/s, and the QPS of the entire cluster reached nearly 1 million.

With the development of the Internet, high reliability, high concurrency, and cost reduction and efficiency improvement have become the real challenges faced by major companies. The demand for performance optimization has become more urgent. From distributed systems to algorithm optimization in code blocks, they have become things you have to deal with in your daily work. For developers, performance optimization has also changed from a bonus factor to a popular skill. Lack of relevant knowledge will make it difficult to stand out in interviews or work.

Challenges in Performance Optimization #

However, as someone who has been through it, I find that many learners and practitioners face many challenges in Java performance optimization, such as:

  • When encountering “performance optimization” problems in work scenarios, they often rely on guesswork and feelings, using temporary remedies to cover up the problems. It may seem like the problem is solved, but the same problem will occur again next time. The reason is the lack of methodology, guidance, and tool support.
  • In the process of skill cultivation, due to long-term exposure to CRUD (create, read, update, delete) operations, the lack of a high-concurrency practice environment makes it possible to imagine “performance optimization” only through theoretical knowledge, without understanding its true nature and practical processes in work experience.
  • In career promotion, focusing only on functional development and lacking knowledge of component design principles, along with a lack of deep thinking and summarizing, makes it difficult to complete advanced tasks such as designing high-concurrency and high-performance systems. It becomes challenging to showcase one’s skills at work, and challenging tasks are often left to those who are prepared.

In summary, once encountering a “performance optimization” problem, few people can analyze it from a holistic perspective and ultimately find the bottleneck and optimization methods. Performance optimization is the deep waters of software engineering and a standard for measuring the competence of a programmer.

Key Aspects of Java Performance Optimization #

As the saying goes, knowing oneself and the enemy enables one to win every battle. To overcome the challenge of “performance optimization,” one must first understand its characteristics and grasp its key aspects and essence.

As a required topic in interviews, many candidates have expressed that they often find themselves in a dilemma when faced with questions from interviewers, not knowing how to answer. For example, many people don’t understand the difference between buffering and caching. The answer to such questions can only be achieved through systematized organization, relying on scattered knowledge is not effective. You need the ability to relate different subjects in order to further elevate the fragmented knowledge in interviews with depth and breadth, which will impress the interviewer.

Performance optimization is a systematic engineering task that requires both breadth and depth of technical knowledge from engineers. It not only requires proficiency in programming languages but also a deep understanding of the interaction between operating systems, JVM, and framework principles. It requires multidimensional and comprehensive analysis and investigation.

Furthermore, many people may be able to solve problems when they encounter them, but firefighting measures can only temporarily remedy surface-level issues and fail to truly identify the root causes. This temporary fix only sets the stage for future problems. In fact, many performance issues are often deeply hidden, such as the performance issues caused by Spring AOP, which are difficult to diagnose.

For example, some people pay attention to whether switch statements or if statements are faster at an extremely detailed level, but they cannot truly solve performance problems. Why is that? Although they have taken the action of “performance optimization,” their approach is incorrect. This level of optimization at the micro level has a minimal impact on performance improvement. Moreover, excessively pursuing performance in details can make code obscure and difficult to maintain, leading to focusing on insignificant details over the fundamentals. In fact, performance optimization requires us to pay more attention to overall effects, while considering reliability, scalability, and extreme exceptional scenarios. This is the only way to demonstrate the value of performance optimization.

Practice is more important than theory. Performance optimization is not about optimizing a specific, singular scenario. Different scenarios require different methods. For example, if your business is sequential and time-consuming, you cannot simply improve performance by adding CPU resources. If your business is parallel, you cannot obsessively optimize every line of code. You need to coordinate various resources to emphasize optimization in weak areas in order to achieve the best results.

In the past, you may have relied solely on intuition or started acting before thinking, unable to discover the essence. However, in this course, I will explain the correct approach to you, so that you can have a rational basis for performance optimization.

Course Design #

In this course, I have compiled classic cases of Java performance optimization and provided a large number of code examples to help you understand real-world business scenarios.

The course is divided into 5 modules with a total of 21 articles. I will comprehensively explain the theoretical analysis, tool support, case studies and interview points, as well as JVM optimization from four perspectives:

  • Module 1: Theoretical Analysis - Addressing common performance optimization issues, we will first explain various performance metrics and then analyze commonly used optimization methods, including business optimization, reuse optimization, computation optimization, result set optimization, resource conflict optimization, algorithm optimization, and efficient implementation. By completing this module, you will understand how to describe performance and have an overall impression of performance optimization.
  • Module 2: Tool Support - To do a good job, you must have the right tools. This module will introduce tools for assessing the performance of operating system devices, including practical command line analysis. We will also introduce JMH, the most effective benchmark testing tool in Java, as well as some applications for monitoring JVM performance. The goal of this module is to provide you with performance measurement tools to prepare you for practical work.
  • Module 3: Practical Cases and Frequently Asked Interview Questions - This module is the main content of the course. Combining the theoretical analysis and tool support from the previous modules, we will explore numerous practical cases to delve into specialized performance scenarios. We will also address frequently asked interview questions for each scenario, provide guidance on optimization strategies, and aim to help you quickly come up with suitable optimization approaches when encountering similar performance problems.
  • Module 4: JVM Optimization - This module can greatly improve system performance. It mainly covers basic knowledge of garbage collection and examines the performance improvements achieved by JIT. Finally, it lists some common optimization parameters and coding requirements. By completing this module, you will master common optimization measures related to JVM.
  • Module 5: Special Presentation - Lastly, I would like to introduce a Spring Boot service optimization case, covering scenarios such as Tomcat, Undertow, JVM, and networking, as well as summarizing optimization methods and job interview experiences. I hope that through this comprehensive case, you will master optimization techniques from the system level to the application level.

What You Will Gain #

Establish a comprehensive knowledge system of performance optimization. You can systematically learn relevant knowledge instead of acquiring fragmented pieces. The practicality and strong foundation of the theoretical analysis will allow you to have clear guidance and a solid basis for practical work.

Ability to develop optimization strategies for online applications. Master various practical diagnostic tools, apply them flexibly, pinpoint bottleneck points in applications, and develop optimization strategies. Correct methods are more important than efforts. With the right mindset and methods, you can avoid deviating from the track and wasting effort on trivial matters. I will also share a significant amount of knowledge about operating systems, enabling you to better evaluate application performance.

Abundance of practical experience sharing. As the most hardcore content of this course, I will analyze popular middleware, commonly used utility classes, and knowledge points in the JDK through practical analysis and sharing of experiences to reproduce real-world business scenarios. This will help you gain a deep understanding of the entire process of performance optimization.

Obtain a weapon to secure job offers in interviews. Most of the cases in this course are the Achilles’ heel of Java interview questions. I will directly point out the high-frequency exam points, allowing you to provide suggestions for performance optimization overall and conduct targeted optimization in detail.

Instructor’s Message #

Finally, performance optimization is both a formidable obstacle and an alchemy to enhance your capabilities. I hope this course can make this challenging issue become approachable, easy to understand, and straightforward, giving you the feeling of “Oh, it’s that simple!”. I hope it will bring you the long-lost joy of learning and make your learning practical.

In addition, I collaborated with the Lagou Education platform last year to create the course [《Understanding the Java Virtual Machine in Depth》 (already completed)]. It received good user reviews. The course on the Java Virtual Machine can be considered as a complement to the Java performance optimization course, and I recommend you to study and understand it.

Java performance optimization requires a breadth and depth of knowledge. Let us master the mindset for performance tuning, practice more, and elevate our coding skills.