.NET 4.0 introduces new support for dispatching invocations on dynamically typed objects. As far as I can make out, this involves: no change to the CLR new types in the BCL new compilers that convert new syntax into usages of the new types In the Java space, folks are discussing adding a new dynamicinvoke bytecode to the JVM such th...
I'm working through the Clojure examples in Stuart Halloway's "Programmming Clojure" and I've hit a snag when using binding: (def foo 10) ; => '#user/foo foo ; => 10 (binding [foo 42] foo) ; => 10 (binding [user/foo 42] foo) ; => 10 (binding [user/foo 42] (var-get #'user/foo)) ; => 10 Why won't it give me 42? ...
Let us say that I want to create a class MyString which is a wrapper for java.lang.String. I have added a new method called reverse. public class MyString { private String text=null; public MyString(String foo){ text=foo; } public String reverse(){ // implementation omitted return reversedString; } } Now Str...
I've been wondering this for a while. Please give quantitative data to support your answer. Related: Is there a significant difference between Windows, Mac, and linux JVM performance? ...
Over the past year I've made huge improvements in my application's Java heap usage--a solid 66% reduction. In pursuit of that, I've been monitoring various metrics, such as Java heap size, cpu, Java non-heap, etc. via SNMP. Recently, I've been monitoring how much real memory (RSS, resident set) by the JVM and am somewhat surprised. ...
Please help!!! I wonder how can I reconcile the following error: "JVM cannot use large page memory because it does not have enough privilege to lock pages in memory"? The settings are: set JAVA_OPTS=-Xms20g -Xmx20g -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+UseLargePages -Duser.timezone="GMT" %DEBUG% This happen on Windows 2003 ...
I am trying to write my own JVM. Can you point me to some existing open source implementations. Thanks. ...
Wish the latest Java runtimes (1.5 or 1.6) is the applet pluggin suppoed to use the Internet Explorer web stack to download the .jar file? The reason I ask is I can't see the request in Fiddler. More background - I'm trying to troubleshoot this error: load: class at.workforce.applet.VMVersionApplet.class not found. java.lang.ClassNotFou...
I am building some software using Clojure as a backend, and I'd like to use a JVM based solution for the front-end. I am open to any of the frameworks & languages out there. I know about Compojure / Webjure / Ring, but I feel like there may be more mature options. Thanks! ...
I'm currently using sun's java 1.6 on a SL4 cluster. For some reason, the 1.6 JVM is starting up with an impossibly large heap, and cannot start: java -version Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. If I start it with e.g. -Xmx1800M, then it...
Hi, Say I have a dual-core windows laptop and I run a multithreaded application on it. Does the JVM run only on one core or do the JVM and the OS somehow communicate to split threads between the two cores? A similar question has been asked for C#. I've also had a look into a couple of Sun's performance white papers. I read that threads...
Why is Object[].class.isAssignableFrom(String[].class) == true, while String[].getSuperClass() or getGenericInterfaces() could not get Object[]? I checked the source of JDK, but i don't think i can get the answer myself. For now, I know JDK uses tree to store the relationship between Classes, and depth to indicate its level, Class::isAs...
Hi, What i usually do concerning the jvm heap size is setting the max value really high to avoid the infamous OutOfMemoryException. However, this strategy (or lack of strategy) doesn't seem to be really smart. :-). My question is how to choose the min and max values, and the difference between the two (should max-min be small or big?...
There are Database Administrators (DBA) and Unix|Windows System Administrators. There are likely soon to be Cloud Administrators. There are hordes of "administrators" who are tasked with administering and managing numerous large-system JVMs running on/in various stacks, yet I've honestly met very few of them who have any real understan...
It has been thirteen years between the initial public release of Java 1.0 (1996) and the current stable release 1.6.0_16 (2009). During those thirteen years the following notable releases have been made: JDK 1.0 (January, 1996) JDK 1.1 (February, 1997) J2SE 1.2 (December, 1998) J2SE 1.3 (May, 2000) J2SE 1.4 (February, 2002) J2SE 5.0 (...
For Java SE there are several JVM's available for running in production on x86: IBM J9 Oracle JRockit - http://www.oracle.com/technology/products/jrockit/index.html Apache Harmony - http://harmony.apache.org/ The one in OS X (if a Mac) which appears to be Sun with Aqua Swing. OpenJDK plus some custom offerings for running on a serve...
Wrote a quick Java proggy to spawn 10 threads with each priority and calculate pi (4*atan(1) method) with BigDecimals 500,000 times each, join on each thread and report the elapsed time for run method. Yeah, prob'ly not the best example, but keeping it basic. I'm aware of Bug4813310 It is non-trivial to do in C, but can we assume that...
I see many deployments where IT groups run effectively nothing but a JVM application stack inside a VM (vmware, &c) instance. I guess I consider the JVM to be a formal VM: what real benefit is it to run your Java application stack inside another VM? ...
The Java data type byte for example holds data from -128 to 127 in a single byte on storage. To enable to distingush between - 1 to -128 from 0 to 127 would require extra data which would take the datatype obver its allocated storage. Admittedly it would only take 1 extra bit but it still goes over. How does java do this? ...
I have basic idea on Kilo Virtual Machine on Mobiles , I have clear idea of how JVM works class loaders , Executable Engine,Method Area etc . Technically how KVM differs from JVM ? Does KVM increases the execution time as compared to JVM ? Any Performance Oriented difference ? Memory management Thanks ! ...