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Common monitoring jvm commands A pure smile The command involved in this article is jps jstat jmap jstack jinfo jps Command format jps [options] [hostid] [] optional options parameter list -l: output the full name of the main class or jar path-q: only LVMID(local virtual machine id) is output, that is, the unique id of the ...

Class lifecycle The first five steps together are the traditional whole process of class loading Among them, 2, 3 and 4 are collectively referred to as the link stage Class loads and initializes When the virtual machine is started, the main class specified by the user is initialized, which is the class where the main method is sta ...

Using JavaAgent to test the size of objects Author: Ma Bingbing http://www.mashibing.com Object size (64 bit machine) Observe virtual machine configuration java -XX:+PrintCommandLineFlags -version Common object Object header: markword 8ClassPointer: - XX:+UseCompressedClassPointers is 4 bytes, not open is 8 bytesInstance data Reference ...

The class loader mentioned earlier. We all know that classes need to be loaded into memory. How much memory does this class need to occupy in memory? When we call a method, how does the JVM apply for memory and ensure data consistency? Data consistency Before understanding data consistency, first understand the CPU. ALU: Calculation unit Re ...

SpringMVC 1. What is spring MVC Is a lightweight, MVC based web application layer framework that encapsulates servlets MVC: M: Model, the Model layer, refers to javaBean, which is used to = = process data== ​ javaBean: Entity class, business processing, i.e. Service, Dao V: View, the View layer, refers to html or jsp pages in the pro ...

Absrtact: the garbage collection mechanism is the best example of a daemon thread because it always runs in the background. This article is shared from Huawei cloud community< This article takes you to understand the garbage collection mechanism in Java >, author: Hai Yong. introduce In C/C + +, programmers are responsible for the cre ...

1. Atominc Atom Package There are 12 classes in the Atomic package, and there are four ways to update atoms: the basic type of atomic update, the array, the reference, and the field. The classes in the Atomic package are basically wrapper classes implemented using Unsafe. Basic Classes: AtomicInteger, AtomicLong, AtomicBoolean Reference type ...

Java JVM diagnostic tool Arthas https://arthas.aliyun.com/doc/ Official website introduce Arthas is an open source Java diagnostic tool of Alibaba, which is deeply loved by developers. When you encounter the following similar problems and are helpless, Arthas can help you solve them: Which jar package is this class loaded from? Why are al ...

Class lifecycle Loading: find the Class fileVerification: verify format and dependencyPreparation: static field and method tableResolution: resolve symbols to referencesInitialization: constructor, static variable assignment, static code blockUsingUnloading Class loading timing When the virtual machine starts, initialize the main class spe ...

Java class loading steps 1. Loading The main task of the loading phase is to convert the classes in the. Class file into java.lang.Class objects. The specific steps are as follows: Get the binary byte stream defining a class through the fully qualified name of the classThe static storage structure represented by this byte stream is tra ...