Although written for many years of Java code, but basically only the JVM when blackbox processing. The book on the JVM has also seen several books, but the results are poor. See OPENJDK code? Not interested. I've had a few weeks of free time, so I decided to write a JVM in the Go language and conquer the JVM monster!Wh
"Great haste makes great waste"
JVM startup process
The JVM is the environment in which the Java program runs, as well as an application process of an operating system, so it has its own lifecycle and its own code and data space.
The JVM works and features mainly refers to the operating system loaded into the JVM,
Jdk:java Development ToolKit (Java SDK), including the Java Runtime Environment JRE (Java Runtime envirnment), a bunch of Java tools (javac/java/ JDB, etc.) and Java-based class libraries (that is, Java APIs include Rt.jar).The JDK includes the JRE primarily because of the tools and examples available in the JDK and requires JRE support to run.Jre:java Runtime enviromental (Java Runtime Environment). That is what we call the Java platform, all Java programs must be under the JRE to run. Includes
Java Programmers sometimes need to understand JVM-related parameters, either out of curiosity or work needs. Some parameters are listed in the Oracle document (Click here). Not all parameters are listed, and some parameters are enabled or disabled by default, in some cases, setting a parameter does not take effect. Sometimes you want JVM to do something, but you don't know which parameter can be used. The f
Articles in the JVM series (II): Garbage collection mechanism and jvm garbage collection
As a programmer, it is far from enough to know how to use it. At least, you need to know why it can be used, that is, what we call the underlying layer.
So what is the underlying layer? I don't think this can be generalized. In my current knowledge: for Web developers, TCP/IP, HTTP, and other protocols may be the underl
The JVM heap size setting is a deep dive. It requires both a high degree of understanding and implementation of the architecture and a deep understanding and mastery of the internal language mechanism.First, you need to have a preset and monitor the JVM heap size. See this article to select five suggestions (5 tips for proper Java heap size) for the appropriate Java heap size ), in fact, this article mainly
Schematic diagram of the Java Virtual Machine ---- JVM runtime data zone, virtual machine ---- jvm
JVM Runtime data zone (JVM Runtime Area)In fact, it refers to the division and allocation of computer memory space during JVM running. This article will discuss the
Memory management and garbage collection are critical points for the JVM, and it is important to understand the basic strategies of memory management and garbage collection for the analysis of Java performance.1. During the process of running the program, a large number of objects are created, most of which are short-period objects, a small part is a long-period object, and for short-period objects, frequent garbage collection is required to ensure th
JVM Memory composition and GC-related content see previous articles: JVM memory composition GC Policy memory request.Example of the meaning of JVM parameters is shown in example analysis
Parameter name
Meaning
Default value
-xms
Initial Heap Size
1/64 of physical Memory (
The default (minheapfreeratio pa
1) Method Area2) Heap3) Java Stacks4) PC Registers5) Native Method StacksJava's JVM's memory model can be roughly divided into 3 zones:Heap Area:1. All objects are stored, each containing a class-corresponding information. (The purpose of class is to get operation instructions)2.JVM only one heap area (heap) is shared by all threads, and the heap does not hold basic types and object references, only the object itselfStack area:When a thread executes a
This is a creation in
Article, where the information may have evolved or changed.
Although written for many years of Java code, but basically only the JVM when blackbox processing. The book on the JVM has also seen several books, but the results are poor. See OPENJDK code? Not interested. I've had a few weeks of free time, so I decided to write a JVM in the Go la
Chapter 2 JVM memory allocation and Chapter 2 jvm allocation
Note: This blog is mainly based on the following three books:
Distributed Java applications: basics and practices
Deep understanding of Java Virtual Machine (version 2)
16 lessons that break the basic skills of programmers
Note: For details about the JVM memory structure, refer to Chapter 1
JAVA advanced interview Summary-JVM, java interview-jvm
1. Sun HotSpot VM is a self-embedded Virtual Machine in JDK and Open JDK. It is also the most widely used Java virtual machine.
2. JVM Memory Distribution
Program counter: it is a small memory space and can be seen as the row number indicator of the bytecode executed by the current thread. The basic functi
Deep understanding of Java Virtual Machine: JVM advanced features and best practices (in-depth analysis of JVM Based on issues such as memory management and high concurrency)
Provides a comprehensive and in-depth analysis of JVM based on core content such as memory management, execution subsystem, programming compilation and optimization, and efficient concurrenc
A deep understanding of one jvm [memory region] and a deep understanding of the jvm Region
Before the beginning of this article, we need to declare that this series of articles discuss the hot spot VM. Most of the ideas in this article are based on Zhou Zhiming, who deeply understands the Java VM: JVM advanced features and best time. if I have any misunderstandin
Jvm and jvm virtual machines
What is the relationship between jvm and jre?
JRE: Java Runtime Environment,Includes Java virtual machines(Jvm)Java core class library and supporting files. It does not containIn JDKDevelopment tools, such as Compilers, Debugger, and other tools. So the relationship is clear at a glance.
Jvm-related parameters, tuning, and jvm parameter tuning
Common jvm parameters are as follows:
-Xmx1024m: Set the JVM maximum available memory to 1024 MB.-Xms1024m: Set JVM to enable the memory to be 1024 MB. This value can be set to the same as-Xmx to avoid
JVM tuning summary, jvm Tuning
Heap size settingsThe maximum heap size in JVM has three restrictions: the data model (32-BT or 64-bit) of the relevant operating system; the available virtual memory limit of the system; and the available physical memory limit of the system. Generally, 32-bit systems are limited to Gbps ~ 2 GB; 64 indicates that the operating sy
Jvm supports Simple testing of the maximum number of threads and jvm supports the maximum number of threads.
Recently, to test the maximum number of concurrent threads in Openfire, a large number of threads are required to simulate the client. I am always confused about the number of threads that a JVM instance can open. Therefore, I plan to test the number of th
Chapter 6 JVM garbage collector (2) jvm garbage collection
The previous chapter records several common garbage collectors. For details, see chapter 5 JVM garbage collector (1).
1. G1
Note:
From the Perspective, compared with CMS, G1 is different only in the final "filter and recycle" section (CMS is a concurrent cleanup). In fact, the overall heap memory divi
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