What should I (as a Java programmer who doesn't know anything about JVM internals) do when I come across a JVM crash? In particular, how would you produce a reproducible test case? What should I be searching for in Sun's (or IBM's) bug database? What information can I get from the log files produced (e.g. hs_err_pidXYZ.log)? ...
Examining a Java runtime with CMS (Concurrent-Mark-Sweep) GC enabled, what is the definition of the CMS space in the logs below? Shall I assume it is the tenured space? I see the following lines of a minor-major-minor GC event 23.481: [GC 23.481: [DefNew: 1051K->128K(1152K), 0.0029912 secs] 11925K->11027K(13600K), 0.0031697 secs] [Tim...
Can someone please provide some insight into the the following verbosegc lines on a Java runtime with CMS GC enabled? Specifically: Does the event at 29.490 indicate heap location of the highwater for marking? What is the preclean phase and what is it doing different than marking? What is the reset phase? Why would that take time to...
We have a desktop application using JNI that occasionally causes the JVM to crash. Luckily the JVM produces a hs_err_pidXXXX.log file, which is quite useful in debugging such errors. However, it always seems to go to the current working directory, and it's annoying to dig it from there, since our other log files all go to a specific "log...
In Production system,like Banking application running in Linux environment, How do I distinguish running Java threads and native threads? In Linux there will be Parent process for every child process, and they say 0 is the parent of all the process, will there be a Parent thread of all the forked Java threads? How do I know which Java ...
Hello, I am working with a java application deployed on an HP server via WebLogic 10.3. Version info: WebLogic Version 10.3 OS Version B.11.23 $ java -version java version "1.6.0.03" Java(TM) SE Runtime Environment (build 1.6.0.03-jinteg_05_feb_2009_11_19-b00) Java HotSpot(TM) Server VM (build 11.0-b16-jre1.6.0.03-rc2, mixed mode) ...
I recently received a Nokia 5000 phone. Now I want to write software for it. Trouble is, I don't know Java. Now I've heard of other languages which supposedly make possible development without recourse to Java, languages like CellularBASIC (which looks a bit like QBASIC) and Hecl (which seems to be based on Tcl). Are these the only on...
If I've writen a Scala program, can I compile it in a way so that anybody with a standard Sun Java JVM can run it? I guess the Scala compiler would have to include the Scala-specific API code in the compiled project? The reason I'm interested is that our class projects can usually be delivered in whatever language one prefers, but TAs gr...
Let me first give an example. Imagine you have a single server running a JVM application. This server keeps a collection of N equations, once for each client: Client #1: 2x Client #2: 1 + y Client #3: z/4 This server includes an HTTP interface so that random visitors can type https://www.acme.com/client/3 int their browsers and see ...
As a C++ programmer becoming more familiar with Java, it's a little odd to me to see language level support for locking on arbitrary objects without any kind of declaration that the object supports such locking. Creating mutexes for every object seems like a heavy cost to be automatically opted into. Besides memory usage, mutexes are an ...
Hello, I am doing a compilers discipline at college and we must generate code for our invented language to any platform we want to. I think the simplest case is generating code for the Java JVM or .NET CLR. Any suggestion which one to choose, and which APIs out there can help me on this task? I already have all the semantic analysis don...
I'm looking for a really simple / limited scripting language for the JVM or the Bean Scripting Framework but can't find any. I need the following operators: + - * / maybe ** (power) maybe sqrt ... and the ability to define Double type variables to create expressions like (A+B)/2 The script may not call any JVM code (maybe with ...
We have an application deployed in Websphere application server 7. Its deployed and functioning in various environments. But it gave a method not found exception in one new env. On digging deeper we found that a particular class was present in 2 jars and the class from the "wrong" jar was getting loaded in the new env. i went through the...
I have setup eclipse to attach to a local JVM. But when I try to do the same for a machine over the network I get "connection timed out exception". How do I go about debugging this issue? I tried: lsof -i :8787 on the remote machine, and it appears that a java process is in fact listening on that port. What else could be wrong and h...
When I create a multi-threaded program and I use methods such as Wait or Signal to control threads among other things, does JVM control all the thread state changes or does the underlying OS have anything to do with it. ...
Dear All! I use Hibernate in an extension-like server-side application, and I put my binaries to the Extensions folder of the server application. The problem is, that if I run the server, the root folder is the root folder of the server application, and not the root of the binaries. Thus, Hibernate searches the config file in that folde...
Currently I am working on a Java agent to assemble memory stats. With the help of the instrumentation API I can get a hold of the classes (and manipulate them). With plain Java I can get an estimate of the resources used for each object. So far, so good. The question I am faced with right now is "how to get a hold of every Object instan...
-Xms is to specify initial heap size or minimum heap size? I see lot of places with lot of different answers. Some like second answer here, say that it is for initial heap and some like here say that its minimum heap size. Or is it that the minimum size itself is the initial size? ...
I have a dll that contains legacy C code, I call this dll via JNI, but sometimes the C code crashes and causes the JVM to terminate. Is it there a way to avoid JVM crash? Can I handle the JNI fault and let the JVM survive? :) ...
Here's a phrase that I heard a lot throughout high school and university computer science classes: "That's not an issue for modern JVMs." Usually this would come up in discussions about overall performance or optimization strategies. It was always treated as a kind of magical final answer, though, as if it makes issues no longer w...