main content:
G1 GC raised uncertainty Region, each idle Region is not ready for a fixed age, it is flexible, demand-driven, so G1GC on behalf of the advanced nature.
This document is mainly to learn the Java language students, junior programmers using GC reference suggestions and experience, highlighting the G1 GC. China's software industry has been developing for decades, from the current development of the industry point of view, difficult to have a simple software development company, currently popular cloud computing, networking and enterprise integration is actually integrated IT technology, which programmers need to have comprehensive capabilities. Author strive to achieve a comprehensive dissemination of knowledge, rather than just explain for the Java virtual machine and GC tuning, each chapter has also sought to support the actual case.
This document includes the following aspects: JVM Basics, GC basics, G1 GC-depth introduction, G1 GC tuning recommendations, JDK comes with tools introduction.
JVM tuning of case-based practical learning route guidance
GC garbage collection GC data entry video preview 761.16MB
In-depth understanding of JVM & G1 GCPDF technical documentation
Learning technical documentation directory: it is too large, so only the part of the knowledge point shots out of the rough introduction, each section has a more detailed content.
The first chapter JVM & GC Basics:
JVM Java language is cross-platform, high development remain fundamental, not a JVM, Java language will lose runtime environment. For performance optimization Java program must not be avoided for tuning the JVM, JVM with the continuous development of our responses are constantly follow the changes, memory usage gradually become more complex. All high-level language need to protect garbage collection, so GC's that important.
This chapter describes and addresses the following issues, which are also the basis of the whole chapter.
Why do we need to understand the JVM and GC, which is based on your reading of this book.
GC understand the basis of common terms of knowledge, authors and readers need to define the term unified.
Learn the basics of the JVM, including the heap, stack, the method area.
To better understand the JVM and GC good knowledge base.
Chapter 2, JVM & GC-depth knowledge
A garbage collection process a trace, track all of it passes a pointer to the object that is currently used, in order to find all the objects that can be referenced, and then re-used in any heap memory during this trace was not found. The common language runtime garbage collector also compacts the memory in use, to reduce the work needed for the heap space. This is the traditional definition of garbage collection.
Garbage collection is the basic guarantee for sustainable operation of a Java application, it be segmented according to generational way for each object, similar in each country train carriages snow, different each car passengers aboard, but also in certain time is recovered, empty, the life cycle of the object will be set according to certain rules. Only by understanding the JVM ', understand the GC, can really write efficient Java applications.
This chapter describes and addresses the following issues, which are also the basis of the whole chapter.
● understand the JVM memory and related knowledge.
● Learn about common garbage collection algorithm, which is the fundamental goal of GC achieved.
● understand the basic concepts of the GC.
● understand the characteristics of various types of GC.
● To better understand the G1 GC good knowledge of storage each.
Chapter 3, G1GC application examples
G1 GC gave us a lot of command line options, that is, parameters that a Class Boolean type beginning, "+" indicates that this option is enabled, "_" means turn off the option. Another type of digital assignment, no Boolean type beginning. In this chapter we will explain in detail each a sense of common options, and with a practical program as an example. In this way for readers to Chapter 4, Chapter 5 ready.
Note that the option based on the example in this chapter JDK8U45 run.
This chapter describes and addresses the following issues, which are also part of the practice of later chapters.
Determining a simple code program as an example.
Learn G1GC comes with a variety of command-line options.
Understand the various options run output singly or in combination after.
G1GC output to log some explanation.
Chapter 4, in-depth G1GC
Wherein G1 GC using incremental manner, parallel computing, exclusive operation, and for copying the target compression technology itself. At the same time, shortening the respective levels by a multistage manner parallel marking (marking, re-marking, clear phases) of the dwell time.
We can often see in American movies easily avoid security actor, a man armed enemy lair scene. I want to say is G1 GC multi-level, no interval investigation design, so that this scenario can only happen on the TV screen.
This chapter is a whole chapter of the conceptual level core chapters, describes and addresses the following issues.
●-depth study of basic notions of G1 GC.
● G1 GC-depth study of the design concept.
●-depth understanding of all types of properties G1 GC.
● Section 5 is made ready for performance optimization knowledge of G1GC.
Chapter 5, G1 GC Performance Optimization
Why Internet company so tired? Because all problems in the production environment occur, defects, they must be addressed immediately or avoid, otherwise there is no way to estimate the loss appeared to restore. Performance optimization engineers of all types of engineers, the most tired of a sub-sub-type of work, research and development teams need them to be able to quickly locate and solve problems found in the process of running a software product, especially a memory leak, the application hangs for no reason, heap overflows, empty situation pointers, etc., and even need them in the absence of external tools to help debug and find the direct cause of the problem by reading the code and resolve. In this chapter we will optimize the performance of the program for the G1 GC-by - in-depth explanation.
This chapter describes and addresses the following issues, which is the whole chapter of conceptual level core chapters.
Further in-depth study of the G1 GC concepts.
● G1 GC-depth study of the design concept.
● further use of the characteristics G1 GC.
Chapter 6, JVM diagnostic tools introduced
This chapter describes and addresses the following issues, these major learning tool for SA.
● What is the Serviceability Agent tool?
● understanding of the relevant concepts, tools and practices introduced basic functions.
● Understand tool extensions, plug presentations.
● to summarize some frequently asked questions.
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