to collect memory).
Long-term survival of the object into the old Age. The virtual machine defines an age counter for each object, and if the object passes through 1 minor GC then the object will enter the survivor area, then each time after the minor GC so the Object's age plus 1, know to reach the threshold object into the old age Area.
Determines the age of the object dynamically. If the sum of all objects of the same age in the survivor area is greater than half the size of Survivor
JVM monitoring tools-Introduction to several common tools and jvm monitoring-common toolsIntroduction to JVM monitoring tools
Jdk provides a powerful GUI-based jvm monitoring tool, which can be seen in the jdk bin directory, such as jconsole, jvisualvm, and oracle jrockit jvm's jrmc.exe.Introduction:
GUI tools
(the new generation uses the replication algorithm to collect memory ).3. Long-lived objects enter the old age. The Virtual Machine defines an age counter for each object. If the object passes through the Minor GC once, the object enters the same vor area. After that, every time the object passes through the Minor GC, the age of the object increases by 1, know that the target reaches the threshold and enters the elderly area.4. dynamically determine the age of the object. If the total size of a
JVM advanced features-2. Distribution, layout, access process, and JVM layout of jvm objects in the heap
After introducing the data area of the jvm runtime, I will explain other details about the data in the memory to see how they are created, laid out, and accessed.
I. Object Creation
1. Object allocation
There ar
[JVM] 1. jvm VM parameters-X and JVM-x
Options that begin with-X are non-standard (not guaranteed to be supported on all VM implementations), and are subject to change without notice in subsequent releases of the JDK.Non-standard options starting with-X (cannot be guaranteed to be supported by all JVM implementations)
A better-performing Web server JVM parameter configuration:-server//Server Mode-xmx2g//JVM the maximum allowable allocated heap memory, on demand-xms2g//JVM the initial allocated heap memory, generally and xmx configured to avoid the JVM reallocating memory after each GC. -xmn256m//Young generation memory size, entire
Visualvm is Sun's openjdk project. It aims to create a complete set of problem solving tools for Java applications. It integrates a visual tool with multiple JDK command tools. It is mainly used to monitor JVM running conditions, you can use it to view and view heap dump, thread dump, memory object instance, GC execution, CPU consumption, and class loading. Java developers can use visualvm to create logs of
, except when using JNI or local libraries. When opened, it reports various JNI events, such as when the local library is loaded, when the method bounces back, and again, in different JVM versions, the output changes.
5. Command-line-x
I've listed the command-line options that are available in the JVM, but there are a few more that need you to find out for yourself, Run command line parameter-X, and list
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 J
Common debugging Parameters for the JVM:–VERBOSE:GC display information on the output device when a memory collection occurs on a virtual machine-xloggc:filename logging of GC-related log information to a file for analysis-xx:-heapdumponoutofmemoryerror Export the relevant information in this heap when an oom is first encountered-xx:onerror= "-XX:-P rintclasshistogram The column information of the print class instance after Ctrl-break, same as Jmap-hi
The JVM is a virtual machine and a specification, and he follows the design principles of the von Neumann architecture. Von Neumann architecture, it is pointed out that the computer processing data and instructions are binary number, using stored procedures to store in the same memory without distinction, and sequential execution, instruction by the operation code and address code, the operation code determines the type of operation and the number of
JVM Stack resolver operation problem, that is, how the program executes, or how to process the data; The JVM heap solves the problem of data storage, where the data is placed, where it is placed, and what is stored in the JVM heap is the object. The JVM stack is a reference to the base data type and the objects in the
JVM runtime memory structure and JVM runtime Memory Structure
1. JVM Memory Model
JVM runtime memory = shared memory zone + thread memory Zone
1). Shared Memory Zone
Shared Memory zone = persistent band + heap
Persistent tape = method zone + others
Heap = Old Space + Young Space
Young Space = Eden + S0 + S1
(1) Pers
JVM principle and optimization, and JVM principle Optimization
The jvmjob principle and special point are that the operating system is installed with jvmthrough jdk's java.exe, and the following four steps are used to complete the JVM environment.
1. Create a JVM loading environment and Configuration
2. Load
Java applications are running on the JVM, but do you know anything about JVM technology? This article (the first part of the series) describes how classic Java virtual machines work, such as: the pros and cons of Java authoring once, Cross-platform engines, garbage collection basics, classic GC algorithms, and compiler optimizations. The following article will talk about
One server installs zookeeper and starts, then installs monitor dubbo-monitor-simple-2.8.3 on another server to unzip the installationModifying a configuration fileDubbo.container=log4j,spring,registry,jettyDubbo.application.name=simple-monitorDubbo.application.owner=#dubbo. registry.address=multicast://224.5.6.7:1234dubbo.registry.address=zookeeper://113.52.182.149:54111?backup=113.52.182.150:54111#dubbo.
The JVM's full name is Java Virtual Machine (Java VM), which shields the software and hardware differences associated with each computer platform.
in the coming days, I'll learn the JVM in the form of blogging, to make myself more aware of the Java
This series of articles is "Deep analysis of Javaweb Technology Insider" and "in-depth understanding of Java Virtual Machine" Summary, welcome everyone to spit together, progress together
JVM-Concepts and jvm-Experiences
I recently took the time to review the JVM concept. Now I will record my experiences.
Part 1: abstract a JVM concept diagram based on learning to describe the composition and basic functions of each major component.
Part 2: Describe the content based on the structure diagram.
1) --
JVM memory management, garbage collection, and jvm Memory Management
I. JVM Memory Structure
The Java Virtual Machine divides the memory into several different management zones. These regions have their own purposes. Based on their characteristics, they undertake different tasks and use different algorithms for garbage collection. It consists of the following par
. According to the above line, the building contains three rooms: "special room", "Hall", and "waiting for room ".
Simply put, the monitor monitors threads entering this particular room. It ensures that only one thread can access the data and code in the special room at a time.
[2] monitor implementation in JAVA
In the Java Virtual Machine, each Object (Object and class) is associated with the
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