jvm-arguments

I see this parameter in all kinds of places (forums, etc.) and the common answer it help highly concurrent servers. Still, I cannot find an official documentation from sun explaining what it does. Also, was it added in Java 6 or did it exist in Java 5? (BTW, a good place for many hotspot VM parameters is this page ) Update: Java 5 does not boot with this parameter. butterchicken In order to optimise performance, the JVM uses a "pseudo memory barrier" in code to act as a fencing instruction when synchronizing across multiple processors. It is possible to revert back to a "true" memory barrier

What is the default value for XX:MaxDirectMemorySize? John Gardner From http://www.docjar.com/html/api/sun/misc/VM.java.html i see: 163 // A user-settable upper limit on the maximum amount of allocatable direct 164 // buffer memory. This value may be changed during VM initialization if 165 // "java" is launched with "-XX:MaxDirectMemorySize=<size>". 166 // 167 // The initial value of this field is arbitrary; during JRE initialization 168 // it will be reset to the value specified on the command line, if any, 169 // otherwise to Runtime.getRuntime.maxDirectMemory(). 170 // 171 private static

I would like to retrieve an error message that explains why the jvm failed to load. From the examples provided here: http://java.sun.com/docs/books/jni/html/invoke.html I extracted this example: /* Create the Java VM */ res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args); if (res < 0) { // retrieve verbose error here? fprintf(stderr, "Can't create Java VM\n"); exit(1); } In my specific case I'm providing invalid arguments in the vm_args and would expect to see what I get on the command line: "Unrecognized option: -foo=bar" On further testing it looks like the jvm is putting the message I want

I have several systems that all need to load the same properties to the JVM. I can use the -D flag to load one property at a time, but i am looking for something that will load all the properties in an entire file at one time. For instance: I could just add --options-file=blah.properties to all jvms on my network, once, and from then on only change the properties file, which could be a single central file over a network share. Thank you, EDIT: Any arguments or commands must also work in a windows environment. Therefore any bash or scripting hacks specific to unix will not work. That's roughly

I have a Java 7 application using JVM ARGS: -Xms1024m -Xmx2048m , and it runs pretty well. After I upgrade to Java 8, it runs in error state with Exception: Exception in thread "main" java.lang.OutOfMemoryError: GC overhead limit exceeded at org.hibernate.engine.StatefulPersistenceContext.addEntry(StatefulPersistenceContext.java:466) at org.hibernate.engine.TwoPhaseLoad.postHydrate(TwoPhaseLoad.java:80) at org.hibernate.loader.Loader.loadFromResultSet(Loader.java:1439) at org.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:1332) at org.hibernate.loader.Loader.getRow(Loader.java:1230)

Suppose our code has 2 threads (A and B) have a reference to the same instance of this class somewhere: public class MyValueHolder { private int value = 1; // ... getter and setter } When Thread A does myValueHolder.setValue(7) , there is no guarantee that Thread B will ever read that value: myValueHolder.getValue() could - in theory - keep returning 1 forever. In practice however, the hardware will clear the second level cache sooner or later, so Thread B will read 7 sooner or later (usually sooner). Is there any way to make the JVM emulate that worst case scenario for which it keeps