best jvm profiler

JVM-runtime data zone and JVM-runtime data ZoneRuntime data Zone1. Program Counter Register: it is a small memory space and can be seen as a line number indicator of the bytecode executed by the current thread. --> The bytecode interpreter selects the next bytecode instruction to be executed by changing the value of this counter, the basic functions such as branch, loop, jump, exception handling, and thread

Deep understanding of JVM (1)-Java memory region, jvm-java 1. Data Area During Running During Java program execution, the Java Virtual Machine divides the memory it manages into several different data regions. The memory managed by the Java Virtual Machine will include the following runtime data areas: 1. Program counters 1) The Program counter (Program CounterRegister) is a small memory space. Its functio

JVM garbage collection algorithm and jvm garbage collection 1. Mark-cleanup algorithm: the most basic garbage collection algorithm. Just like its name, the algorithm consists of two steps: Marking and cleanup: first, marking the objects to be cleansed, after marking is completed, all marked objects are recycled in a unified manner. The disadvantage of this algorithm is efficiency, low efficiency in the mark

JVM-class loading mechanism and jvm-Loading MechanismVirtual Machine Loading Mechanism The Virtual Machine loads the class data described from the class file to the memory, verifies the data, converts the parsing and initialization, and finally forms the Java type that can be directly used by the virtual machine, this is the class loading mechanism of virtual machines. Class loading time Class is loaded to

Complete parsing of JVM-class file-field table set, jvm-class fieldField table set This class file has been parsed for a long time. this section describes the category magic number, version number, main board number, constant pool entry, constant pool, access flag, class index, parent class index, and interface index set. the field table set should be included below. Then the set of interface indexes is the

JVM tuning summary, jvm Tuning Auxiliary InformationJVM provides a large number of command line parameters and prints information for debugging. There are mainly the following: -XX: + PrintGCOutput Format: [GC 118250 K-> 113543 K (130112 K), 0.0094143 secs][Full GC 121376 K-> 10414 K (130112 K), 0.0650971 secs] -XX: + PrintGCDetailsOutput Format: [GC [DefNew: 8614 K-> 781 K (9088 K), 0.0123035 secs] 1

I. Introduction of TOOLSJconsole: A Java GUI monitoring tool that can display a variety of data in a tabular format. Remote server VMS can be monitored through remote connections. A GUI program written in Java, used to monitor VMS, and to monitor remote VMS, is very easy to use and very powerful. Command line to play Jconsole, select the process is OK.It is important to note that before running the Jconsole, the environment variable display must be set up first;2, the use of the process2.1 Enter

When executing a Java program, the Java Virtual Machine divides the memory it manages into several different data regions. These regions have their own purposes, as well as the creation and destruction time. Some regions exist with the startup of virtual machine processes, some regions are created and destroyed Based on the startup and termination of the user's thread. The memory managed by the Java Virtual Machine will include several runtime data regions, as shown in:650) This. width = 650; "s

Oom?Java.lang.OutOfMemoryError:java head space heap memory overflowJava.lang.OutOfMemoryError:Permgen Space Java Eternal Overflow, that is, methods to overflow, generally because of the emergence of a large number of classes and JSPs, or the use of Cglib reflection mechanism,This can be resolved by changing the size of the method area and modifying it in the form of a similar-xx:permsize=64m-xx:maxpermsize=256m. In addition, too many constants, especially strings, can cause the method area to ov

there are many other languages based on the JVM's syntax, such as Scala,groovy,jruby and so on.ASM is a tool that knows about JVM directives, or the class file format.When the JVM loads the class, it provides some functionality that allows the human to modify the class object, or the byte stream that the class eventually loads into the JVM.By using ASM to modify the class byte stream, we modify the behavio

Brief IntroductionJava.exe is the execution program of the Java classfile. An execution shell that loads JVM. dll (in windows, the following uses Windows as an example, Linux and Solaris are actually similar, for: libjvm. So), this dynamic Connection Library is Java The actual operation of the virtual machine. This document describes how the java. exe program finds and loads JVM. dll. Dynamic library, and c

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

System CentOS6.4 Yum installed Tomcat6 and jdk1.6, the installation configuration process is as follows: Http://www.111cn.net/sys/CentOS/72007.htm The deployment of two projects A and B in Tomcat, as well as the time of memory overflow error in the deployment times, the system CPU load is soaring, and a, B, and only multiple a, or just multiple B-project systems are deployed separately for normal operation. View Log error: Outofmemoryerror:permgen space ....Query data learned: Non-heap overfl

This article is transferred from https://zhuanlan.zhihu.com/p/25713880. Basic concepts of the JVMThe Chinese name of the JVM is called a Java Virtual machine, which is a virtual computer run by software technology that simulates a computer.The JVM also acts as a translator, and the Java program we write is not directly identifiable by the operating system, and the JVM