@Override
  public void refresh() {
    Runtime rt = Runtime.getRuntime();
    vmStats.setInt(cpusId, rt.availableProcessors());
    vmStats.setLong(freeMemoryId, rt.freeMemory());
    vmStats.setLong(totalMemoryId, rt.totalMemory());
    vmStats.setLong(maxMemoryId, rt.maxMemory());

  }
Statistics related to a Java VM. Currently they all come from {@link java.lang.Runtime}.
geode-core/src/main/java/org/apache/geode/internal/statistics/VMStats.java