Hello, I need to check if some option which can be passed to JVM is explicitly set or is it have default value. To be more specific: I need to create one specific thread with higher native stack size than the default one, but in case then user want to take care of such things by himself by specifying -Xss option I want to create all thre...
I'm looking at developing an application that takes advantage of the Pulse smart pen. I would rather do it in python than java. Its not clear what version of the jvm runs on the pen, as evidence here in the tech specs Are there limitations on whether or not jython and jruby will run on mobile version of the jvm? ...
JVM Spec 2nd Edition is dated by 1999. Which important updates since then (like dynamicinvoke) should I consider to learn? This is in course to understand internals of the modern JVM implementations (HotSpot particularly). ...
I'm trying to figure out what can cause this error in Java: Invalid access of stack red zone 0x115ee0ed0 rip=0x114973900 Has anyone ever encountered this error message? It's literally killing the JVM and everything stops there. I'm currently using this version of Java:(on OS X 10.6) java version "1.6.0_15" Java(TM) SE Runtime Envir...
Given a Java class file (ClassName.class) with bytecode version X is there a general way to convert this class file from being represented in bytecode version X to being represented in bytecode version Y? Assumptions: The source code is not available. The class file is the only available representation of the class. The class file is ...
Is there some way to see the native code produces by the JIT in a JVM? ...
I'm reading this article about how JVM invokes methods, and I think I got most of it. However, I'm still having trouble understanding the need for invokeinterface. The way I understand it, a class basically has a virtual table of methods and when calling a method with either invokevirtual or invokeinterface this virtual table is consult...
I read somewhere that there is such optimization as Objects Inlining. It collocates two objects together if they have the same life-time scopes and there is a lot of reads between them. And GC also treat them as one to move from one generation to another. But I didn't find any mention about this optimization on java.sun.com to be sure ...
I have already read various accounts of Clojure vs. Scala and while I realize that both have their place. There are a few considerations that I haven't acquired a complete explanation on when it comes to comparing both Clojure with Scala: 1.) Which of the two languages is generally faster? I realize that this will vary from one langua...
Hi Was working my ... off on a handin project this evening, and suddenly the JVM started crashing on me. I've been able to create a simple program that can reproduce the crash, and have submitted it to Sun, but I wondered if anyone in here could take a look at the program, and tell me if I'm doing something stupid (ie there's an easy wa...
Hi, I have a web-app, built and compiled in Eclipse, which I want to deploy to my Tomcat 6 (I want to do it manually) and I get a UnsupportedClassVersionError exception which means the JVM tomcat is running is older than the one my eclipse is running. After some checking I see that in the tomcat manager window it says: JVM Version-1.5.0_...
Sometimes, I'll run a program that accidentally contains an infinite loop or something. Eclipse will let me continue editing the program, but be super slow. How can I stop it? (Do I want to restart the JVM?) Restarting eclipse itself always works, but that breaks my workflow. ...
I'm trying to figure out if there's a way to determine the JVM startup properties from within a running java process. Specifically I'm trying to find out where parameters such as -Xmx (max heap size) and -XX:MaxPermSize are stored. I'm running Sun's 1.6 jvm. If you're wondering why I want to do this, I have a number of JVM webservers ...
What is the easiest way to obtain a list of all classes used while running a Java application? Assume that com.package.Foo.main is invoked by running: java com.package.Foo After running the program I'd like to have a list of all classes that have been used while running the program: cat classes-used.txt com.package.Foo com.package.F...
I took a look at some new languages for JVM. Two of them are gathering much interest these days: Clojure and Scala. But in my humble opinion, both of them are not ideal. (Let's keep it a speculation, cause I don't want to damage myself discussing..) What I actually see as a tricky move is MS's invention - F#. Simply moving the OCaml lan...
Consider the following two Java classes: a.) class Test { void foo(Object foobar) { } } b.) class Test { void foo(pkg.not.in.classpath.FooBar foobar) { } } Furthermore, assume that pkg.not.in.classpath.FooBar is not found in the classpath. The first class will compile fine using the standard javac. However, the second class won't c...
Clojure is a functional lisp, reportedly not at all object-oriented, even though it runs on the JVM, a VM designed for an object oriented language. Clojure provides identical interfaces for iterating over lists and vectors by abstracting them to an interface called seq. This is even implemented internally using a Java interface called ...
Since switching to JRE 6, my server's code cache usage (non-heap) keeps growing indefinitely. My application creates a lot of classes at runtime, BUT these classes are successfully unloaded during the GC process. I can see these classes getting unloaded in the gc logs and also the permGen usage stays constant. I specifically make sure in...
In java, common IO operations involving streams, files and the like can be somewhat annoying. Thus I (and many others) tend to reach for things like commons-io to ease the pain. In scala - are there some better idioms/classes/libraries to use (I know of scala.io.Source etc for reading in text files - but what about streams etc). Is it ...
What is the fastest language that runs on the JVM? Scala? Groovy? JRuby? ...