The JVM is the basis for the Java language to be cross-platform and maintain high development. Without the JVM, the Java language will lose its operating environment. Performance optimization for Java programs cannot avoid tuning for the JVM. With the continuous development of the JVM, our countermeasures are constantly following and changing, and the use of memory has gradually become more and more complicated. All high-level languages need the protection of garbage collection mechanisms, so GC is so important.
If you want to learn GC, you first need to understand why GC is needed.
As the business handled by the application becomes larger and more complex, and there are more and more users, the normal progress of the application cannot be guaranteed without GC. And the GC that often causes STW can't keep up with the actual demand, so it will continue to try to optimize the GC.
HotSpot has so many garbage collectors (Serial GC Parallel GC Concurrent Mark Sweep GC), why release Garbage First (G1) GC? The reason is this.
This document mainly provides references and experiences of using GC for students and junior programmers learning Java language. It is difficult for software companies to develop. The current popular cloud computing and Internet of Things companies are actually the integration of comprehensive IT technologies, which requires programmers with comprehensive capabilities.
The author of this material strives to achieve comprehensive dissemination of knowledge, not just explaining Java virtual machine and GC tuning, but also strives to have actual case support for each chapter. This information specifically includes the following aspects: JVM basic knowledge, GC basic knowledge, in-depth introduction to G1 GC, G1 GC tuning suggestions, introduction to the use of JDK's own tools, etc.
After reading through this material, the reader can gain an in-depth understanding of many topics and general knowledge about G1 GC performance tuning. Readers can also use this material as a reference, and jump directly to the corresponding chapters to find answers to topics of interest.
Due to space reasons, I cannot share all the contents of the notes here, only some screenshots of the contents of the notes can be shown, and the full PDF can be downloaded at the bottom of the article!
Chapter 1: JVM & GC Basics
Through the study of this chapter, you can understand the following:
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Why we need to know about JVM GC is the basis for you to read this book.
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To understand the basic common terminology knowledge of GC, authors and readers need to unify the terminology definitions.
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Understand the basics of the JVM, including the heap, stack, method area, and more.
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Prepare your knowledge base for an in-depth understanding of the JVM and GC.
Chapter 2: JVM & GC in-depth knowledge
Through the study of this chapter, you can understand the following:
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Learn about the JVM and memory.
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Understand common garbage collection algorithms, which is the fundamental goal of GC implementation.
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Understand the basic concepts of GC.
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Understand the characteristics of various types of GC.
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Make a good knowledge reserve for an in-depth understanding of G1 GC.
Chapter 3: G1 GC Application Examples
Through the study of this chapter, you can understand the following:
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Identify a simple code program as an example.
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Learn about the various command line options that come with the G1 GC.
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See the output of running each option individually or in combination.
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Some explanation for G1 GC output logs
Chapter 4: G1 GC in depth
Through the study of this chapter, you can understand the following:
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Learn various basic concepts of G1 GC in depth.
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Learn more about the design philosophy of the G1 GC.
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Learn more about the various features of the G1 GC.
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Prepare knowledge for the performance optimization scheme for G1 GC in the next chapter.
Chapter 5: G1 GC performance optimization scheme
Through the study of this chapter, you can understand the following:
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Further in-depth study of various concepts of G1 GC.
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Learn more about the design philosophy of the G1 GC.
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Take advantage of the features of the G1 GC in depth.
Chapter 6: Introduction to Using JVM Diagnostic Tools
Through the study of this chapter, you can understand the following:
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What is the Serviceability Agent tool?
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Understand related concepts, basic functions of tools, and practical introduction.
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Learn about the extended functions of the tool and the introduction of plug-ins.
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Summarize some frequently asked questions.
write at the end
In general, there is no one-trick performance tuning cheats or all-inclusive performance encyclopedia that can turn you into a seasoned GC performance tuning expert. A fair number of GC performance issues also require specialized knowledge and skills to resolve. Performance tuning is very much an art. The more GC performance problems you solve, the better your craft will be. We should not only care about the continuous evolution of GC, but also actively understand its design principles and design goals.
The analysis of the Java GC mechanism in this document is simple and in-depth. After reading the excellent practice of Java memory recycling for big data, I benefited a lot. After the application of many technical details, the product performance has been significantly improved. It is a very worthwhile read!
For the full version, please see the download below!