jvm-arguments

Given these two commands A: $ java -Xms10G -Xmx10G myjavacode input.txt B: $ java -Xms5G -Xmx5G myjavacode input.txt I have two questions: Since command A reserves more memory with its parameters, will A run faster than B? How do -Xmx and -Xms affect the running process and the output of my program? It depends on the GC your java is using. Parallel GCs might work better on larger memory settings - I'm no expert on that though. In general, if you have larger memory the less frequent it needs to be GC-ed - there is lots of room for garbage. However, when it comes to a GC, the GC has to work on

Considering the following command line java -Xms128m -Xms256m myapp.jar Which settings will apply for JVM Minimum memory ( Xms option) : 128m or 256m ? Depends on the JVM, perhaps the version...perhaps even how many paper clips you have on your desk at the time. It might not even work. Don't do that. If it's out of your control for some reason, compile and run this the same way you'd run your jar. But be warned, relying on the order of the options is a really bad idea. public class TotalMemory { public static void main(String[] args) { System.out.println("Total Memory: "+Runtime.getRuntime()

(Note that when I say "JVM", I really mean "Hotspot", and I'm running the latest Java 1.6 update.) Example situation: My JVM is running with -Xmx set to 1gb. Currently, the heap has 500mb allocated, of which 450mb is used. The program needs to load another 200 mb on the heap. Currently, there is 300mb worth of "collectable" garbage in the heap (we'll assume it's all in the oldest generation.) Under normal operation, the JVM will grow the heap to 700 mb or so, and garbage collect when it gets around to it. What I would like in that situation is for the JVM to gc first, then allocate the new

There was a change in Java 1.7 in the way the default Locale is get from the OS. There are methods of restoring the old behaviour e.g. by setting the flag -Dsun.locale.formatasdefault=true when starting a JVM instance. I would like to set this flag permanently so that I don't have to specify it in command line arguments each time when I start a JVM instance. Is there a file or any other possibility to change the default settings for JVM? Something like the Eclipse.ini file but for the JVM itself? a_horse_with_no_name You can set set environment variable JAVA_TOOL_OPTIONS in your OS. All Java