I cannot for the life of me find a definition of what the Java VM flag CMSClassUnloadingEnabled actually does, other than some very fuzzy high-level definitions such as “gets rid of your PermGen problems” (which it doesn’t, btw). I have looked on Sun’s/Oracle’s site, and even the options list doesn’t actually say what it does. … Read more
I thought it would be great to have a comparison between _JAVA_OPTIONS and JAVA_TOOL_OPTIONS. I have been searching a bit for one, but I cannot find anything, so I hope we can find the knowledge here on Stackoverflow. JAVA_OPTS is included for completeness. It is not part of the JVM, but there is a lot … Read more
I am getting this error message when I start Eclipse Helios on Windows 7: Failed to create the Java Virtual Machine My eclipse.ini looks as follows: -startup plugins/org.eclipse.equinox.launcher_1.1.0.v20100507.jar -vm P:\Programs\jdk1.6\bin –launcher.library plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.0.v20100503 -product org.eclipse.epp.package.jee.product –launcher.defaultAction openFile -showsplash org.eclipse.platform –launcher.XXMaxPermSize 512m –launcher.defaultAction openFile -vmargs -Dosgi.requiredJavaVersion=1.5 -Xms120m -Xmn100m -Xmx1024m My JAVA_HOME is correctly set as far as … Read more
In which languages are the Java compiler (javac), the virtual machine (JVM) and the java starter written? 9 Answers 9
It 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? 14 Answers 14
This question already has answers here: What is a StackOverflowError? (15 answers) Closed 6 years ago. I’ve looked everywhere and can’t find a solid answer. According to the documentation, Java throws a java.lang.StackOverflowError error under the following circumstance: Thrown when a stack overflow occurs because an application recurses too deeply. But this raises two questions: … Read more
I have installed JDK 8 and trying to run Eclipse. I am getting following warning message: Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=512m; support was removed in 8.0 What are the reasons for ignoring this VM option? 6 Answers 6
How to activate JMX on a JVM for access with jconsole? 12 Answers 12
A generic method that can return a random integer between 2 parameters like ruby does with rand(0..n). Any suggestion? 23 Answers 23
Is there any way I can get a list of all running threads in the current JVM (including the threads not started by my class)? Is it also possible to get the Thread and Class objects of all threads in the list? I want to be able to do this through code. 13 Answers 13