what's running on my VM?

[William Stafford]

Is there a way to find out what processes are running on a Java VM?

When we shut Tomcat the console window that our app opened in does not close. We are thinking that this is because something associated with the app is still running.

However, just in general, I think it would be interesting to see what's running.

Thanks in advance for any guidance.

-=beeky

[Ulf Dittmer]

It's possible to list all the threads that are running in a JVM. The following piece of code does this. (Yes, it's so old that it generates HTML directly in a servlet - JSP didn't exist back then :-)

 
private void getThreadInfo (PrintWriter output) {
 
// Get the top level thread group
 ThreadGroup adam = getAdam(Thread.currentThread().getThreadGroup());
// Get the count of active threads in the system
 int num = adam.activeCount();
 
// Get all of the active threads in the system
 Thread list[] = new Thread[num];
 int x = adam.enumerate(list);
// if (x != num)
//return;
 
// Display all of the active threads in the system
 output.println("<p><b>Threads</b><table border=1><tr>");
 output.println("<th>Group</th><th>Name</th><th>Priority</th><th>Daemon</th><th>Alive</th></tr>");
 
 for (int i=0; i<x; i++) {
if (list[i] == null) continue;
String threadName = list[i].getName();
String groupName = list[i].getThreadGroup().getName();
 output.println("<tr><td>" + groupName
 + "</td><td>" + threadName
 + "</td><td>" + list[i].getPriority()
+ "</td><td>" + (list[i].isDaemon() ? "Yes" : "No")
+ "</td><td>" + (list[i].isAlive() ? "Yes" : "No")
+ "</td></tr>");
 }
 output.println("</table>");
 }
 
// Recursively calls itself to find the top level thread group
private ThreadGroup getAdam (ThreadGroup tg) {
 ThreadGroup parent = tg.getParent();
 if (parent == null)
 return tg;
 
 return getAdam(parent);
}

[ February 21, 2007: Message edited by: Ulf Dittmer ]

[William Stafford]

Thanks Ulf. I didn't realize that thread info was that readily available. I guess my question was not really 'advanced' java.

-=beeky