best jvm profiler

When we found in the IDE console:The value of the persistent generation set for the JVM is too small, you need to open the window->preferences->java->installed JRE in Eclispe, click the Edit button on the right, and the default VM Arguments option, increase the value of-xx:permsize and-xx:maxpermsize.If you understand JVM performance tuning, you can learn about the relationship from Jstat monitoring. The fo

JVM tuning-calculate the active data size and jvm tuning Active Data Active Data, sometimes called survival data, refers to the size of long-lived objects in the Java heap when the application is in stable running state. In other words, the space occupied by the Java heap after FullGC in the stable running state of the application (memory usage ). 1. Importance of active data computing The calculation of t

As we all know, the JVM used to be interpreted in the past, but later in the history of the revision also added to the implementation of the compilation. So in general the JVM is comprised of interpretation execution and compilation execution. This part does not belong to the scope of the JVM, has been compiled, most of them are lexical analysis and the like, the

JVM class loading mechanism ---- 2. jvm Loading Mechanism The first phase of the class loading mechanism is: 1. Use a fully qualified Class name (package name and Class Name) to obtain the binary byte stream (Class file) that defines this Class ). You can use the jar package, war package, network retrieval, and JSP file generation methods. 2. Convert the static storage structure represented by this byte st

Jvm memory growth troubleshooting examples and jvm troubleshooting examplesTroubleshoot jvm memory Growth Troubleshoot the problem that the jvm memory usage continues to increase. record it and take it as a warning. The O M team found that the jvm memory usage of the applic

Jvm running data distribution and jvm Data Distribution I have a deep understanding of jvm (java se7 of this version) Data Area During java Runtime When executing a java program, the java Virtual Machine divides the memory into several different stages and has different time. Different purposes First Program counter: A small memory space in the

JVM garbage collection algorithm and jvm garbage collection 1. Reference Counting Collector) The reference counting algorithm is a simple but inefficient algorithm. Its main principle is as follows: each object in the heap has a reference counter; when the object is referenced, add 1 to the reference counter; when the referenced object is left empty or out of scope, the reference counter minus 1. This metho

Garbage collection in Jvm and Jvm garbage collection I. Concept of garbage collection Memory collection in Java is the memory collection during Jvm runtime. The areas to be recycled include the method area and Java heap. Because of program counters, Java Virtual Machine stacks and local method stacks are automatically recycled at the end of methods or threads, so

JVM Automatic Memory Management-Java memory area and memory overflow exceptions, jvm-java Abstract: JVM memory division, which may cause memory overflow exceptions. 1. JVMRuntime memory Zone The JVM divides the memory managed by the Java program into the following areas: 1.1Program counters The program counter is a sm

Chapter 8 JVM performance monitoring and troubleshooting tools (2), jvm troubleshooting Note: This blog is mainly recorded in "deep understanding of Java Virtual Machine (version 2)" Note: For details about JVM performance monitoring and troubleshooting tools on the command line, see Chapter 7 JVM performance monitorin

Comparison between Dalvik Virtual Machine and JVM: Dalvik Virtual Machine JVM The Dalvik virtual machine has many similar features as the Java Virtual Machine, including GC, JIT, and JNI. The main difference is that the file format and instruction set are different, and the features of the two are compared and discussed below.Difference1: File Format Dalvik's virtual machine files use the dex format, while

Let's talk about the JVM class loading mechanism and jvm loading mechanism. I wrote this article a few months ago to deeply understand the Java class loading principle. I briefly talked about my understanding of Java class loading. Recently, I also studied the book "deep understanding of Java virtual machines, I have a more systematic understanding of the JVM cl

Java basic questions (JVM), java basic questions jvm 1. What is a Java Virtual Machine? Why is Java called a platform-independent programming language "? A Java virtual machine is a virtual machine process that can execute Java bytecode. Java source files are compiled into bytecode files executed by Java virtual machines. Java is designed to allow applications to run on any platform without the need for pro

Based on common JVM garbage collection algorithms, jvm garbage collection There are four common garbage collection algorithms in JVM: Mark-clearing algorithm (Mark-Sweep ); Copying ); Mark-Compact ); Generational collection; Next we will introduce them one by one: I. Mark-clearing algorithm (Mark-Sweep) This is the most basic garbage collection algorithm. The alg

JVM-program compilation and code early (during compilation) optimization, jvm-CompilationEarly (Compilation) Optimization I. Javac Compiler 1. Javac source code and debugging The source code of Javac is stored in JDK_SRC_HOME/langtools/src/shares/classes/com/sun/tools/javac. Besides JDK APIs, only the code in JDK_SRC_HOME/langtools/src/shares/classes/com/sun/* is referenced. The debugging environment is sim

Impact of Direct Memory on jvm, jvm memory Direct Memory Direct Memory is an important issue. First, it is neither a part of the running data zone nor a part of the Java Virtual Machine specification. This issue is mainly related to NIO after java1.4, an I/O Method Based on channels and buffers. It can use the Native function library to directly allocate off-heap memory, then, you can use the DirectByteBu

Chapter 5 JVM garbage collector (1): jvm garbage collection (The garbage collection algorithm is a theory, and the garbage collector is a collection algorithm. For details about the collection algorithm, see Chapter 4 JVM garbage collection algorithm.) 1. Seven garbage collectors Serial (Serial GC) ParNew (parallel GC) Parallel Scavenge (Parallel GC collectio

[Switch] Error: no 'server' JVM at 'C: \ Program Files \ Java \ jre6 \ bin \ server \ jvm. dll '. Solution: jre6jvm. dll Problem:Error prompted with java-jar XXX. jar-server-Xms900m-Xmx900m or java-server-versionError: no 'server' JVM at 'C: \ ProgramFiles \ Java \ jre6 \ bin \ server \ jvm. dll '.. SolutionCopy 'serv

Jvm-parent Delegation Model, jvm-parent Delegation Interview Questions Can I write a class called java. lang. System? Answer: Generally, this is not acceptable, but an alternative method can be used to meet this requirement.Explanation: in order not to allow us to write System Classes, class loading adopts a delegation mechanism, which ensures that the class members are given priority and the class members

-xss128k: This JVM parameter is used to configure the stack size to 128kBecause the stack is thread-private (it is unclear to understand the structure of the JVM virtual machine), the exception is generated if we start a thread and call a recursive in the thread./** * VM args:-xss128k * */public class Javavmstacksof {private int stacklength = 1;public void Stackleak () {Stackleng Th++;stackleak ();} publi