Get OS-level system information
You can get some limited memory information from the Runtime class. It really isn't exactly what you are looking for, but I thought I would provide it for the sake of completeness. Here is a small example. Edit: You can also get disk usage information from the java.io.File class. The disk space usage stuff requires Java 1.6 or higher.
public class Main { public static void main(String[] args) { /* Total number of processors or cores available to the JVM */ System.out.println("Available processors (cores): " + Runtime.getRuntime().availableProcessors()); /* Total amount of free memory available to the JVM */ System.out.println("Free memory (bytes): " + Runtime.getRuntime().freeMemory()); /* This will return Long.MAX_VALUE if there is no preset limit */ long maxMemory = Runtime.getRuntime().maxMemory(); /* Maximum amount of memory the JVM will attempt to use */ System.out.println("Maximum memory (bytes): " + (maxMemory == Long.MAX_VALUE ? "no limit" : maxMemory)); /* Total memory currently available to the JVM */ System.out.println("Total memory available to JVM (bytes): " + Runtime.getRuntime().totalMemory()); /* Get a list of all filesystem roots on this system */ File[] roots = File.listRoots(); /* For each filesystem root, print some info */ for (File root : roots) { System.out.println("File system root: " + root.getAbsolutePath()); System.out.println("Total space (bytes): " + root.getTotalSpace()); System.out.println("Free space (bytes): " + root.getFreeSpace()); System.out.println("Usable space (bytes): " + root.getUsableSpace()); } }}
The java.lang.management package does give you a whole lot more info than Runtime - for example it will give you heap memory (ManagementFactory.getMemoryMXBean().getHeapMemoryUsage()) separate from non-heap memory (ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage()).
You can also get process CPU usage (without writing your own JNI code), but you need to cast the java.lang.management.OperatingSystemMXBean to a com.sun.management.OperatingSystemMXBean. This works on Windows and Linux, I haven't tested it elsewhere.
For example ... call the get getCpuUsage() method more frequently to get more accurate readings.
public class PerformanceMonitor { private int availableProcessors = getOperatingSystemMXBean().getAvailableProcessors(); private long lastSystemTime = 0; private long lastProcessCpuTime = 0; public synchronized double getCpuUsage() { if ( lastSystemTime == 0 ) { baselineCounters(); return; } long systemTime = System.nanoTime(); long processCpuTime = 0; if ( getOperatingSystemMXBean() instanceof OperatingSystemMXBean ) { processCpuTime = ( (OperatingSystemMXBean) getOperatingSystemMXBean() ).getProcessCpuTime(); } double cpuUsage = (double) ( processCpuTime - lastProcessCpuTime ) / ( systemTime - lastSystemTime ); lastSystemTime = systemTime; lastProcessCpuTime = processCpuTime; return cpuUsage / availableProcessors; } private void baselineCounters() { lastSystemTime = System.nanoTime(); if ( getOperatingSystemMXBean() instanceof OperatingSystemMXBean ) { lastProcessCpuTime = ( (OperatingSystemMXBean) getOperatingSystemMXBean() ).getProcessCpuTime(); } }}
I think the best method out there is to implement the SIGAR API by Hyperic. It works for most of the major operating systems ( darn near anything modern ) and is very easy to work with. The developer(s) are very responsive on their forum and mailing lists. I also like that it is GPL2 Apache licensed. They provide a ton of examples in Java too!