How to get C like performance in Java. This article was selected as one of DZone's most popular, high-quality posts of 2011. It is now republished as part of a series that will revisit the top articles of 2011 throughout the month of January 2012. Overview Java has many areas which can be slow. However for every problem there is a solution. Many solutions/hacks require working around Java's protections but if you need low level performance it is still possible.
Java makes high level programming simpler and easier at the cost of making low level programming much harder. It makes me wonder why you would write more than 10% of your code in C/C++ for most projects. One way to get C-like performance is to use C via JNI for key sections of code. Note: Most of these suggestions only work for standalone applications rather than applets.
Note 2: Use at your own risk. Fast array access One area Java can be slower is array access. Arbitrary memory access Using less memory This is not as much of an issue as it used to be. Faster Startup times. AppDynamics.com. Performance | Xebia Blog - Part 2. In my current position as Performance Engineer and in my past position as a Middleware Architect I did quite some work with closed source performance monitoring and analysis tools (i.g. CA Wily and later AppDynamics). These tools are both expensive but also do quite a good job most of the times. In the same field there are more tools, but all in the same price range for as far as I know. To name some: Foglight, Dynatrace, Newrelic, JXInsight, Tivoli Performance Viewer, Compuware Gomez. Around 2006 several initiatives to create open source performance monitoring tools for java production environments started to appear. This was mainly because AOP (Aspect Oriented Programming), the technology used in most of these products, was getting attention in the market and there were quite some developments in that area at the time.
I am interested to see how the open source community around these kind of products is evolving. Home — Project Kenai. Discover Java VisualVM 1.3 | @Blog("Baptiste Wicht") Missioncontrol-whitepaper-june08-1-130357.pdf (Objet application/pdf) BTrace: Wiki: UserGuide. Ver. 1.2 (20101020) BTrace is a safe, dynamic tracing tool for Java. BTrace works by dynamically (bytecode) instrumenting classes of a running Java program. BTrace inserts tracing actions into the classes of a running Java program and hotswaps the traced program classes. BTrace Terminology Probe Point "location" or "event" at which a set of tracing statements are executed. Trace Actions or Actions Trace statements that are executed whenever a probe "fires". Action Methods BTrace trace statements that are executed when a probe fires are defined inside a static method a class. BTrace Program Structure A BTrace program is a plain Java class that has one or more public static void methods that are annotated with BTrace annotations.
BTrace Restrictions can not create new objects. A simple BTrace program (1.2) 02.import com.sun.btrace.annotations 04.import static com.sun.btrace.BTraceUtils 07. 08.class HelloWorld { 13. 14. clazz="java.lang.Thread", 15. method="start" 17. void func() { 18. sharedMethod(msg); Terracotta Says 'Goodbye Java GC, Hello BigMemory' We Recommend These Resources Last month, Terracotta told DZone that they were working on a module for Ehcache and Hibernate users that would bypass the Java garbage collection bottleneck. The severely limited heap size allowed by the Java garbage collector (if you don't want to have significant performance issues) is a problem that has plagued the industry for years.
Terracotta believes that today's memory requirements are finally forcing many to address this issue, and now Terracotta has their own answer - BigMemory. DZone interviewed Terracotta CEO Amit Pandey about his company's solution to the GC problem in Java. BigMemory is a snap-in module that provides off-heap memory storage. It is a pure Java solution that works with all JVMs and bypasses the Java garbage collector. Here are the two steps needed to implement BigMemory (when it is released) in Ehcache: 1. 1. 2. 3.overflowToOffHeap="true" maxMemoryOffHeap="4G"/> 4. App Latency Over Time. Comment trouver la charge. Voici la réponse à une question posée par un développeur : comment puis-je trouver la charge moyenne du ou des CPU d’un serveur en Java ? Et le tout, sans écrire de JNI ou d’appel natif ? Java 5 a introduit avec JMX des MBeans simples pour la gestion de mémoire, l’analyse des Threads java, l’accès au système d’exploitation ou encore les paramètres du processus Java en cours.
Dans le package java.lang.managment nous avons les beans suivants : java.lang.management.ClassLoadingMXBeanjava.lang.management.CompilationMXBeanjava.lang.management.MemoryManagerMXBean o java.lang.management.GarbageCollectorMXBean java.lang.management.MemoryMXBeanjava.lang.management.MemoryPoolMXBeanjava.lang.management.OperatingSystemMXBeanjava.lang.management.RuntimeMXBeanjava.lang.management.ThreadMXBean Pour notre problème de CPU et de charge, le bean OperatingSystemMXBean permettra de lire quelques informations sur le système d’exploitation.
Ce bean est disponible à partir de Java 5. Statistiques sur les Threads.