I am trying to use VisualVM to profile a Java (Sun JDK 1.6) standalone application. I have a scripted performance test environment, where I can run my application and get it to report some metrics I care about. Is there some way to get JVM to collect some CPU profiling snapshot which I can later analyze with VisualVM? I am looking for...
I've been getting some strange errors ( perhaps once per day ) after updating a handful of servers to run on Java 6 update 14. The errors are similar to # # A fatal error has been detected by the Java Runtime Environment: # # java.lang.OutOfMemoryError: requested 1759920 bytes for Chunk::new. Out of swap space? # # Internal Error (al...
Have you ever had to justify the choice over using .Net instead of Java based on performance? For a typical high volume transaction processing system that can perform the following operations, Concurrent Database transactions Mathematical computations Interaction with other web services (SOAP/XML, XML-RPC) My approach would be to co...
Hi, I'm currently implementing a .NET wrapper for a Java library by using JNI to start the JavaVM and interacting with Java classes. To be on the save side, I'd like to have unit tests for my code. The Problem I'm facing now is, you only can start the Java VM once per process. There is no possibility to unload the JVM. This makes it ...
Hi I'm running IBM's jvm (jdk 5.0) with the options -XrunHprof:format=b I'm aware that instrumenting jvm with hprof involves a performance penality. I would like to quantify that penality. I know that one way to do this is to take off the hprof profiling and run the application, and compare the application's cpu utilization in both cas...
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 ...
Im building an application that i want to have extended with modules that does some nr crunching and i would like to have R for that. What are my best options for extending my Java application with R? ...
I understand that JVMs can be managed using SNMP and JVMs come with support for JVM-MANAGEMENT-MIB. Is there a way to program/extend the SNMP AGENT functionality which is associated with a JVM? Is there a way to add support for any other proprietary/standard MIBs to the SNMP Agent on JVM, so that I can allow my applications running on ...
Over time, Sun's JVM and JIT have gotten pretty smart. Things that used to be common knowledge as being a necessary micro-optimization are no longer needed, because it gets taken care of for you. For example, it used to be the case that you should mark all possible classes as final, so the JVM inlines as much code as possible. However...
Boo looks like an interesting language, but it appears to be implemented only for the Common Language Infrastructure (CLI), AKA .NET -- at least, I haven't found any other implementation, and I'd especially like one for the JVM, if it exists. So, I thought I'd double check on Stack Overflow -- ARE there any non-CLI implementations of Boo...
What is the default Xms and Xmx settings for the Sun JVM (v 1.4*) if those values are not specified at startup? ...
In C++ I can declare a method "inline" and the compiler is likely to inline it. As far as I understand there is no such keyword in Java. Inlining is done if the JVM decides to do so? Can I influence this decision somehow? ...
I observe in consecutive javacore dumps that the addresses of classloaders are changing in Websphere 6.1 (IBM JVM 1.5.0). The classes below the classloader have unchanged address. So isn't it the same classloader at a new address? E.g. in first javacore 2CLTEXTCLLOAD Loader com/ibm/ws/classloader/CompoundClassLoader(0x0000...
what is the optimal freeheap to totalheap ratio? At what values of this ratio should I consider increasing the heap size/ decreasing the heap size? ...
I read somewhere that java can allocate memory for objects in about 12 machine instructions. It's quite impressive for me. As far as I understand one of tricks JVM using is preallocating memory in chunks. This help to minimize number of requests to operating system, which is quite expensive, I guess. But even CAS operations can cost up t...
The following program, was compiled and tested, it sometimes return the result, and sometimes fills the screen with java.lang.StackOverflowError at scala.BigInt$.apply(BigInt.scala:47) at scala.BigInt.equals(BigInt.scala:129) at scala.runtime.BoxesRunTime.equals(Unknown Source) at bigint$.factorial(fact2.scala:3) at bigint$.factorial(fa...
OMG, eclipse (it's Gallileo, but with previous versions I also had such problems) crashed again, silently as always. That can happen one time per week, but this is really annoying. All I have now is a crash log. Are there any ways of discovering the true reason of these crashes? Header of crash log, can't see anything useful: # # An un...
I build a huge graph in JVM (Scala) which I want to use repeatedly, tweaking algorithms. I'd rather not reload it each time from disk. Is there a way to have it sit in one JVM while connecting from another, where the algorithms are being developed? ...
The Machine is Dual-Core, the OS uses a Multi-Processor kernel. In order to run some performance assessments, I want to set the thread-affinity of the JVM to a single core. However, I am worried that I will get skewed performance measurements as the JVM may be unaware that it is now constrained to a single core, but still using multi-pro...
Hey all, In a recent question asked recently my simple minded answer highlighted many of my misconceptions about Java, the JVM, and how the code gets compiled and run. This has created a desire in me to take my understanding to a lower level. I have no problems with the low level understanding like assembly how ever bytecode and the...