jvm monitoring

"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,

Java.lang.OutOfMemoryError:PermGen Space Found that many people attribute the problem to: Spring,hibernate,tomcat, because they generate classes dynamically, causing permanent heap overflow in the JVM. Then there is a divergence of opinions about how to upgrade the Tomcat version to the latest or even simply without Tomcat. There are also questions about spring that are hotly discussed at the Spring Forum, because spring's use of cblib in AOP creates

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

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

Original link: http://blog.csdn.net/chjttony/article/details/62404571.Websphere JVM-related problem diagnosis:The WebSphere problems caused by the JVM mainly include application server outage and performance degradation, and the characteristics of JVM-related problems are as follows:(1). WebSphere Application Server stops responding:A.websphere server outage.The

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

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

Internal structure diagram of the JVM Java virtual machines are mainly divided into five areas: Method area, Heap, Java stack, PC register, local method stack. BelowSee some important questions about the structure of the JVM. 1. Which areas are shared? Which ones are private? Java stacks, local method stacks, and program counters are created and destroyed with the start and end of user threads.Each thr

more frequently within the JVM, such as regular memory monitoring, JVM health monitoring, and we often need to execute some JSTAT commands to view the GC, as follows: Jstat-gcutil 23483 250 7 This command tells the JVM to print the PID in the console at 23483 for the GC cas

the task queue, and if the task is a non-repeating type of execution, it is removed from the task queue after the task has been executed, and if the task needs to be repeated, it calculates the point in time for the next execution. VM periodic Task Thread Jvm This thread is a thread that is scheduled by the JVM's recurring task, which is created by Watcherthread and is a singleton object.This thread is used more frequently wit

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