I've just upgraded some old Java source which has been running on a Sun Java 1.4.2 VM to Sun Java (JRE) 6 VM. More or less the only thing I had to change was to add explicit datatypes for some abstract objects (Hashmap's, Vector's and so on). The code itself it quite memory intensive, using up to 1G of heap memory (using -Xmx1024m as a p...
What is the use of Strictfp method in java? ...
I have a really simple Java class that effectively decorates a Map with input validation, with the obvious void set() and String get() methods. I'd like to be able to effectively call those methods and handle return values and exceptions from outside the JVM, but still on the same machine Update: the caller I have in mind is not another...
Apologies for the long post, but I wonder if I could get some more eyeballs on this before I submit a bug report to Sun. JVM: 6u11 O/S: Windows XP SP3 Hardware: AMD Athlon 64 X2 4600+ @ 2.41GHz, with 3.25 GB RAM. I believe I have encountered a fault in the JVM where no thread is given a monitor. In the following thread traces, the mon...
I was wondering if something exists (in Java world) able to take an snapshot of the JVM current state with the following features: Do it while an exception is being thrown. Capture local variables, method's arguments, etc. Put it in a handy file which can be used to extract or reproduce in a IDE the situation in your source code. The...
I know that the JVM can do some pretty serious optimizations at runtime, especially in -server mode. Of course, it takes a little while for the JVM to settle down and reach peak performance. Is there any way to take a snapshot of those optimizations so they can be applied immediately the next time you run your app? "Hey JVM! Great job o...
What is the difference between using -agentlib:hprof=cpu=times vs -agentlib:hprof=cpu=sample when running a java class? I know that cpu=sample causes the jvm to sample the call stack at regular intervals, but what does cpu=times do? ...
Hey everyone, I did see the question about setting the proxy for the JVM but what I want to ask is how one can utilize the proxy that is already configured (on Windows). Here is a demonstration of my issue: Go to your Control Panel->Java and set a proxy address. Run the following simple applet code (I'm using the E...
Normally to attach a debuger to a running jvm you would need start the jvm with arguments such as the following: > java -Xdebug -Xrunjdwp:transport=dt_socket,address=1000,server=y,suspend=n Now if I want to debug a process that wasn't started in debug mode, what can I do? This situatoin arrises when a production system (ie started wi...
I'm working on a static analysis tool for .NET assembly. In Java, there is a Descriptor which can be used to represent method or field in a string with specified grammar. for field: double d[][][]; will be [[[D It's useful especially when doing bytecode analysis. Coz it's easy to describe. If there a similar thing in .NET CLR? Or ...
If you decompile the java.lang.Class class in java from the rt.jar library you will notice there is a native method declaration: native ConstantPool getConstantPool(); I played a while ago with class decompilation using Sun's .class file specification and I was able to obtain the constant pool record from each .class file. But that wa...
Lately I've been hearing a lot of people evangelizing that PHP with Resin is actually much faster than with mod_php, but I cannot find any benchmark anywhere. Is it true or just vendor BS? ...
There have been many JVM languages in the recent few years including Javascript, Python, Ruby etc. (full list here: List of JVM Languages). My question is this: why has Sun not come out with a full suite of languages for the JVM just like Microsoft's .NET? With the new version of the JVM, they can make any necessary adjustments for dynam...
What language is Sun's JVM written in? ...
Is there a way to run plain c code on top of the JVM? Not connect via JNI, running, like you can run ruby code via JRuby, or javascript via Rhino. If there is no current solution, what would you recommend I should do? Obviously I want to use as many partials solutions as I can to make it happen. ANTLR seems like a good place to start, ...
I am trying to find out programatically the max permgen and max heap size with which a the JVM for my program has been invoked, not what is currently available to them. Is there a way to do that? I am familiar with the methods in Java Runtime object, but its not clear what they really deliver. Alternatively, is there a way to ask Ecl...
Hi folks! I want to know, how sockets are implemented in the Java Virtual Machine. Is there a native library included? And if, is it a C library? Where can I find information about this topic? The offical Java tutorial on networking does not help me there. Some interesting links would help. Update: Are there any official informati...
How different is Apple's 1.6 Java VM from Sun's? Are there any major performance differences? Do they both share any code, or is Apple's built completely independently? I have been amazed with the performance of the 1.6 JVM under Linux and Windows, especially on floating-point calculations (it is basically neck-and-neck with optimized C...
It's seems rare to read of a Python "virtual machine" while in Java "virtual machine" is used all the time. Both interpret byte codes, why call one a virtual machine and the other an interpreter? ...
Lets say you have interface definition. That interface can be Operation. Then you have two applications running in different JVMs and communicating somehow remotely by exchanging Operation instances. Lets call them application A and application B. If application A implements Operation with the class that is not available in the clas...