Comprendre le fonctionnement de la JVM. Dans le premier article de cette série, nous avons vu comment la JVM optimise notre code.
Ici, intéressons nous à la manière dont la mémoire est gérée et aux différents Garbage Collectors. L’hypothèse générationnelle Toute la gestion de la mémoire opérée par la JVM se base sur une hypothèse générationnelle, résumée par la phrase "la plupart des objets meurent jeunes" ou encore "La plupart des objets créés deviennent très rapidement inaccessibles". L’idée derrière cette hypothèse est que les applications créent de nombreux objets pour leur fonctionnement, mais que seule une faible partie d’entre eux a une longue durée de vie. Ainsi, les différentes étapes d’un traitement génèrent beaucoup d’objets transitoires mais une seule donnée finale. Le graphique suivant résume la quantité d’objets créés par une application en fonction de leur âge. Note : un objet est considéré comme toujours en vie s’il existe un autre objet vivant qui le référence.
Les espaces mémoire utilisables Les collections. High Performance And Smarter Logging. 1.
Summary Logging, often a back-burner activity in the development cycle can actually be the very lifeline of the development team once the application is in production. Assuming that readers are well acquainted with various logging frameworks like Log4J, SLF4J, etc, this article lays guidelines for 'real-world' production logging, examines its influence on the application quality attributes and also rediscovers a forgotten high performance, smarter logging technique with codes and centralized logging. 2 Introduction Logging is often relegated to a back-burner activity while architecting, designing and developing applications or even when enhancing applications. Your application now is out of your development environment - it is not running out of your favorite IDE workbench and much less having a debugger at your service. Logs can be the very lifeline of your production application and should not be taken lightly or as an afterthought. But how many of us actually plan our logs?
Java SE 6 HotSpot[tm] Virtual Machine Garbage Collection Tuning. Note: For Java SE 8, see Java Platform, Standard Edition HotSpot Virtual Machine Garbage Collection Tuning Guide.
The Java™ Platform, Standard Edition (Java SE™) is used for a wide variety of applications, from small applets on desktops to web services on large servers. In support of this diverse range of deployments, the Java HotSpot™ virtual machine implementation (Java HotSpot™ VM) provides multiple garbage collectors, each designed to satisfy different requirements. This is an important part of meeting the demands of both large and small applications. However, users, developers and administrators that need high performance are burdened with the extra step of selecting the garbage collector that best meets their needs.
A significant step toward removing this burden was made in J2SE™ 5.0: the garbage collector is selected based on the class of the machine on which the application is run. When does the choice of a garbage collector matter? The young generation consists of eden and two . Garbage First Garbage Collector Tuning. By Monica Beckwith Learn about how to adapt and tune the G1 GC for evaluation, analysis and performance.
Published August 2013 The Garbage First Garbage Collector (G1 GC) is the low-pause, server-style generational garbage collector for Java HotSpot VM. The G1 GC uses concurrent and parallel phases to achieve its target pause time and to maintain good throughput. When G1 GC determines that a garbage collection is necessary, it collects the regions with the least live data first (garbage first). A garbage collector (GC) is a memory management tool. Allocating objects to a young generation and promoting aged objects into an old generation.
Here, we look at how to adapt and tune the G1 GC for evaluation, analysis and performance—we assume a basic understanding of Java garbage collection. The G1 GC is a regionalized and generational garbage collector, which means that the Java object heap (heap) is divided into a number of equally sized regions. Tuning Garbage Collection for Mission-Critical Java Applications - Tuning Guidelines for Java Garbage Collection, Part 1 « mgm technology blog. I recently had the opportunity to test and tune the performance of several shop and portal applications built with Java and running on the Sun/Oracle JVM, among them some of the most visited in Germany.
In many cases garbage collection is a key aspect of Java server performance. In the following article we take a look at the state-of-the-art advanced GC algorithms and important tuning options and compare them for diverse real-world scenarios. Seen from the point of Garbage Collection, Java server applications have wide varying requirements: Some are high-traffic applications serving a huge amount of requests and creating a huge amount of objects. Sometimes, moderate-traffic applications using wasteful software frameworks do the same thing. In many cases you will find a combination of several of these requirements with different priorities. Out-of-the-Box GC Performance JVMs have improved a lot but still cannot do your job of optimizing the runtime for your application. 1. 2. 3. 4. 5. 6.