Could anyone please tell how jre directory help in the running java programs? I'm calling java interpretor by using java command, and that is in JDK directory, then how could jre directory help in running java programs and jdk for compiling? ...
Hi, I'm trying to programm a self destruction logic. I've already created a global ExceptionHandler which will be processed in some cases. I want to collect some system information before the destruction. One information should be the current heap dump. I found The following page http://blogs.sun.com/sundararajan/entry/programmatically_...
I have a server application that, in rare occasions, can allocate large chunks of memory. It's not a memory leak, as these chunks can be claimed back by the garbage collector by executing a full garbage collection. Normal garbage collection frees amounts of memory that are too small: it is not adequate in this context. The garbage coll...
Hi all, I have three Windows Server 2003 with 2 GB RAM. Server1 tomcat 5.5.25 jvm version SUN 1.6.0_11-b03 Server2 tomcat 5.5.25 jvm version SUN 1.6.0_14-b08 Server3 tomcat 6.0.18 jvm version SUN 1.6.0_14-b08 For the three servers JVM parameters are: -XX:MaxPermSize=256m -Dcatalina.base=C:\Apache Group\apache-tomcat-5.5.25 -Dcata...
I've read that OSGI uses separate classloaders per module which allows modules to use different versions of their dependencies.. while at the same time running all modules in the same JVM. How does this work? If module A uses version #1 of a dependency and module B uses version #2, won't you run into trouble if module A passes an inst...
Our production environment runs 3 32-Bit Java 6 JVMs on each Windows 2003 server. Each heap is at it's max setting (~1.25GB). We are considering moving to new servers and using 64-Bit JVMs. Presumably we can then have one 64-bit JVM on each server that would replace the 3 32-Bit JVMs on each server because of the allowance for a much lar...
I've read the max heap size on 32bit Windows is ~1.5GB which is due to the fact that the JVM requires contiguous memory. Can someone explain the concept of "contiguous memory" and why you only have max 1.5GB on Windows? Secondly, what then is the max heap size on 64 bit Windows and why is this different than what's available on 32 bit?...
I'm trying to optimize the startup time/class loading time of my Java web app because its on the Google App Engine and startup time is important. Is there a way I can turn on some sort of class loading debug messages or someway to see where time is being spent while class loading? I want to see if any specific libraries take a while to...
I have an ordinary project with JUnit tests that are connected to the classes in my Android Project. I want my server to run some JUnit tests in my testproject everytime I commit my code from my Android Project. Is there a best practise to do this? So far I only managed to run the tests when they are a part of a while the JUnit tests a...
Is there Ruby Version Manager equivalent for the Java world? I'm looking for tool which allow me to easily download and install a new JVMs and switch between them. For example: jvm install <version> jvm list //will list installed JVMs on my system jvm use jdk1.6 //will switch my env to jdk 1.6 version, etc. ...
We are getting frequent out of memory errors in our dev. machines We are running webshpere, eclipse, soap UI and maven in it. Our server gets down due to this "out of memory errors" when we restart our applications in websphere 2/3 times, We already increased the virtual memory setting in wesphere to 1GB. So what i did was copied the jr...
I've done changes in an Android native library and installed a new system.img file but am now getting an unrelated Error on startup. I can get past it by swallowing the error but I wanted to know if anyone can explain what the issue is. The Android implementation of Logger.java claims that it is Forcing the LogManager to be initialized ...
multiple webapp running on same tomcat using same jvm. sometime, one webapp that have memory leak will cause entire jvm to crash and affect other webapps. any recommendation how to isolated that without need to use multiple jvm and tomcat ...
In certain well-understood circumstances, our application will open too many sockets (database connections) and reach the maximum open files that the OS allows. We understand this; we are fixing the issue and also bumping up the limit. What we can't explain is why parts of our application don't recover even after the number of connectio...
I am trying to run a java program, but it is taking a default GMT timezone instead of a OS defined timezone. My jdk version is 1.5 and the OS is Windows Server Enterprise (2007) Windows has a Central timezone specified, but when I run the following program, it gives me a GMT time. import java.util.Calendar; public class DateTest { ...
The following simple code reproduces the growth of java.lang.ref.WeakReference objects in the heap: public static void main(String[] args) throws Exception { while (true) { java.util.logging.Logger.getAnonymousLogger(); Thread.sleep(1); } } Here is the output of jmap command within a few seconds interval: user@t1007:~> jmap -d64 -hi...
Is jvm software based? If so in which language is jvm coded? ...
I am looking for something that will make it easy to run (correctly coded) embarrassingly parallel JVM code on a cluster (so that I can use Clojure + Incanter). I have used Parallel Python in the past to do this. We have a new PBS cluster and our admin will soon set up IPython nodes that use PBS as the backend. Both of these systems mak...
I'm trying to create a simple Java app that uses JNI to call some native functions. I've followed the examples in the JNI Programming Guide and can't seem to get them to work. I have the following Hello World program, written in Java: class HelloWorld { private native void print(); public static void main(String [] args) { ...
Referring to my earlier question on incompletely constructed objects, I have a second question. As Jon Skeet pointed out, there's an implicit memory barrier in the end of a constructor that makes sure that final fields are visible to all threads. But what if a constructor calls another constructor; is there such a memory barrier in the ...