!747

!pcall {

m {

  static Map<Long, Thread> idToThread;

  static new WeakHashMap<Thread, Info> infoMap;

  static class Info {

    long cpuTime, measuredWhen; // all in milliseconds

    double percentage; // percentage of CPU used

  }

  static ThreadMXBean mx;

  static boolean cpuTimeSupported;

  static double totalPercentage; // all threads combined

  p {

    mx = ManagementFactory.getThreadMXBean();

    cpuTimeSupported = mx.isThreadCpuTimeSupported();

    if (!cpuTimeSupported) fail("No CPU time info available on platform.");

    while (true) {

      pcall {

        monitor();

        printMostActiveThread();

      }

      sleepSeconds(1);

    }

  }

  static void monitor() {    

    L<Thread> threads = getAllThreads();

    new WeakHashMap<Thread, Info> newInfoMap;

    totalPercentage = 0;

    for (Thread t : threads) {

      Info info = infoMap.get(t);

      if (info == null) info = new Info;

      newInfoMap.put(t, info);

      long nano = 0;

      pcall { nano = mx.getThreadCpuTime(t.getId()); }

      long measured = now();

      long ms = nano/1000000;

      if (info.measuredWhen != 0) {

        long elapsed = measured - info.measuredWhen;

        long used = ms-info.cpuTime;

        info.percentage = Math.max(0, Math.min(100, used*100.0/elapsed));

        totalPercentage += info.percentage;

      }

      info.measuredWhen = measured;

      info.cpuTime = ms;

    }

    infoMap = newInfoMap;

  }

  static void printMostActiveThread() {

    Thread mostActive = null;

    double highest = 0.0;

    for (Map.Entry<Thread, Info> e : infoMap.entrySet()) {

      Thread t = e.getKey();

      Info info = e.getValue();

      if (mostActive == null || info.percentage > highest) {

        mostActive = t;

        highest = info.percentage;

      }

    }

    if (mostActive == null)

      print("No info");

    else

      print("Total CPU used by this VM: " + formatDouble(totalPercentage, 1) + "%. Most active thread: " + mostActive.getName() + " (" + formatDouble(highest, 1) + "% CPU)");

  }

  static L<Thread> getAllThreads() {

    ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();

    ThreadGroup parentGroup;

    while ( ( parentGroup = rootGroup.getParent() ) != null )

      rootGroup = parentGroup;

    Thread[] threads = new Thread[rootGroup.activeCount()];

    int n;

    while ((n = rootGroup.enumerate(threads, true)) == threads.length)       threads = new Thread[threads.length*2];

    L<Thread> l = new ArrayList<Thread>(n);

    for (int i = 0; i < n; i++) l.add(threads[i]);

    ret l;

  }

}