jvisualvm

I want to get a heap dump (suspected memory leak) of a certain Java process. However, when I start the jvisualvm tool, I cannot see any of the running Java processes. I have Google'd around about this and have already found a couple of articles saying that you have to run the Java processes using the same JDK that you start the jvisualvm tool with in order for it to be able to see them. However, as far as I can see, this is already the case. I'm doing everything locally (I have remote access to the machine). A couple of things to consider: The processes are running on a firewalled Windows 2008

Can I check heap usage of a running JVM from the commandline, I mean the actual usage rather than the max amount allocated with Xmx. I need it to be commandline because I don't have access to a windowing environment, and I want script based on the value , the application is running in Jetty Application server Mark You can use jstat, like : jstat -gc pid Full docs here : http://docs.oracle.com/javase/7/docs/technotes/tools/share/jstat.html For Java 8 you can use the following command line to get the heap space utilization in kB: jstat -gc <PID> | tail -n 1 | awk '{split($0,a," "); sum=a[3]+a[4]

Java的自动内存管理机制（ automatic storage management system known as a garbage collector ）省却了很多编码工作，大大地提高了Java的生产力，而且JVM的性能也越来越好，特别是 G1 的出现，改善了垃圾回收中 stop the world 的状况。 也许很多人都没有考虑过这个问题， new一个Object对象到底占用多少内存呢( Object obj = new Object() )？ 这里很明确的是obj是一个指向对象的引用（ reference - there are three kinds of reference types: class types,array types, and interface types ），引用的长度决定了Java的寻址能力，32位的JDK是4字节，64位的JDK是8字节（ 指针未被压缩的情况下 ）。 因为obj对象没有任何数据（field）， 会在堆上为它分配空间吗？如果分配空间，里面存储了什么内容？ 以面向对象的思维来分析，对象封装了数据和行为，是一个统一的整体，虽然obj对象没有数据，但是有行为（Object类定义了12个方法）。 当我们执行完new操作后，obj的值为堆内存的地址，既然obj都指向一块内存了，说明是 会在堆上为其分配空间 的。 那么分配的空间有多大

I run JVisualVM (Windows XP, Sun Java 1.6.0.13, 32 bit client VM) to monitor a distant application (Linux, Sun Java 1.6.0.07, 64 bit server VM). Before starting the actual remote application, I launch on the remote machine jstatd using an all access policy: grant codebase "file:${java.home}/../lib/tools.jar" { permission java.security.AllPermission; }; Then I start the actual app using the command line java -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.port=3333 compileTest.Main From the client machine, I can see the

My specific question has to do with JMX as used in JDK 1.6: if I am running a Java process using JRE 1.6 with com.sun.management.jmxremote in the command line, does Java pick a default port for remote JMX connections? Backstory: I am currently trying to develop a procedure to give to a customer that will enable them to connect to one of our processes via JMX from a remote machine. The goal is to facillitate their remote debugging of a situation occurring on a real-time display console. Because of their service level agreement, they are strongly motivated to capture as much data as possible and

When I run the below mentioned code using NetBeans, the allocated heap size graph resembles a sawtooth shape. I am attaching the screen capture from JVisualVM which shows the heap allocation graph in with a sawtooth shape. The program is a simple infinite loop printing "Hello, World!" into the console. public class HelloWorld { public static void main(String a[]){ while(true) { System.out.println("Hello, World!"); } } } Can anyone explain the reason behind the shape of the graph of used heap? PS : This happens even if I run it without using NetBeans, so it is most likely not related to