jvm memory management

short life cycles (young area) and a long life cycle (old area).Their collection algorithms are different, so the time used is different. GC efficiency is also high, we want to minimize the number of full GC. When the display calls System.GC (), GC does a full collection (both young generation and tenured generation).Tag-Purge algorithm:Replication algorithm:Tag-Cleanup algorithm:Generational collection algorithm:References: Strong references, soft apps, weak references, virtual referencesThe o

operating system stack zone and thread model • Garbage collection • Most objects do not use any objects in a short period of time after they are created, that is, they are not referenced by other objects, that is, they are not referenced by other objects.• Most frequently used objects (old objects) seldom reference newly created objects. Hotspot Memory Management • 64-Bit mode facilitates virtu

There is a "high wall" between Java and C + + that is surrounded by dynamic memory allocations and garbage collection techniques, and people outside the walls want to go in, but the people inside the wall want to come out. --in-depth understanding of Java Virtual machines: JVM advanced features and best practicesThe Java Virtual machine divides the memory it mana

determination The virtual machine cannot be changed to the old age only when it reaches the maxtenuringthreshold age. For example, in the same age in the same vor space, the total size of all objects is greater than half of that in the same vor space, objects greater than or equal to this age can enter the old age without waiting for the specified age. Space guarantee allocation When the young generation experiences minor GC, the virtual opportunity checks whether the average size of each pro

JVM Memory Management　　During the execution of a Java program, the JVM divides the memory into several different data regions. These zones have their own purpose, as well as the creation and destruction of time, and some regions exist as the virtual machine process starts, a

A good Java programmer must understand how the GC works, how to optimize the performance of the GC, and how to interact with the GC in a limited way, because some applications have higher performance requirements, such as embedded systems, real-time systems, and so on, to improve the performance of the entire application only by improving the efficiency of memory management. This article first briefly intro

I. Overview Java is much more convenient than recovering memory from C and C + +, because the JVM automatically allocates memory and reclaims memory for us. In previous JVM storage management, we introduced several areas of

Object (), in fact, the memory space occupied by the instance was still not released. In proposing this proposal, many bloggers or book authors (because there are many bloggers estimate also from the book) meant to eliminate references and instances as quickly as possible, thus inducing the GC to release the memory occupied by the instance when it was garbage collected. At some point, this is done to elim

local variable of a method, a temporary variable within a loop, and so on. 2, Old Undead object: This kind of object generally live relatively long, the age is very big still not dead, but in the final analysis, the old undead object also almost sooner or later die, but also just almost. Examples: cached objects, database connection objects, single instance objects (single case mode), and so on. 3, do not kill the object: Such objects are generally almost immortal once born, they will almost

stacks, dynamic links, method exits, and so on. Each method from the call to the completion of the process, is a stack frame from the stack to the stack process.The local variable table holds the basic data type that the compiler has known, the object reference. The memory space of the local variable table is allocated at compile time and does not change at run time.The error that will occur: 1. StackOverflow, which indicates that the request stack i

JVM introduction automatic memory management mechanism,1. Introduction to JVM (Java Virtual Machine) JVM, short for Java Virtual Machine, is usually a Java Virtual Machine. It serves as the platform basis for Java to Write once and run anywhere, we can clearly figure out th

The compilation and execution of a Java program is as follows:. java--compiles the-->. Class ClassLoader is responsible for loading individual bytecode files (. class) after loading. class, executed by the execution engine, which requires the runtime data area to provide data during execution According to the JVM specification, JVM memory is divided into five pa

various literal and symbolic references, This section is stored in the run-time pool of the method area after the class is loaded.**7) Direct Memory: **nio introduces a channel-to-buffer-based I/O method that can be used to directly allocate out-of-heap memory using the native library and then operate through a Directbytebuffer object stored in the Java heap as a reference to this

Recently busy and picked up "in-depth understanding of Java Virtual Machine" read it again. A deeper understanding of the JVM, let's summarize the structure of the JVM's memory today.JVM memory is divided into several areas: Program counter Virtual Machine Stack Local method Stack Method area Heap Where the program counter, virtual machine sta

designed to be thread-safe. In the JVM specification, there is no mandatory requirement that the method area must implement garbage collection. Many people are accustomed to calling the method area a "permanent generation" because the hotspot virtual machine implements the method area in a permanent generation, so that the JVM's garbage collector can manage this part of the area like the management heap ar

Tag/clear Algorithm. If you have figured out this algorithm, then the last two will be a piece of cake. Because if we want to recycle garbage during the running of a program (program that is the JAVA program we run on JVM), we must make the GC thread cooperate with the thread in the program, in order to smoothly recycle the garbage without affecting the program running.. The method is to stop the whole program (also known as stop the world) when the a

Introduction In the previous chapter we have discussed the implementation of hotspot garbage collector, a total of six implementations of six combinations. This LZ together with you to discuss the six kinds of collectors of their respective power and the power of the combination. In order to facilitate you to watch and contrast, LZ decided to use the original design pattern used in the way, for some collectors, divided into several dimensions to explain these collectors. Client mode and serve

JVM Garbage Collection Policy1. Static memory allocation and recyclingThe memory space is determined at compile time, and the memory space is allocated once the program is loaded. After the program is finished, the corresponding stack frame is revoked, and the allocated static memo