1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 package com.oracle.java.testlibrary;
  25 
  26 import java.lang.management.ManagementFactory;
  27 import java.lang.management.MemoryUsage;
  28 
  29 /**
  30  * Prints memory usage to standard output
  31  */
  32 public class MemoryUsagePrinter {
  33     
  34     public static String humanReadableByteCount(long bytes, boolean si) {
  35         int unit = si ? 1000 : 1024;
  36         if (bytes < unit) { return bytes + " B"; }
  37         int exp = (int) (Math.log(bytes) / Math.log(unit));
  38         String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
  39         return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
  40     }
  41     
  42     public static void printMemoryUsage(String label) {
  43         MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
  44         float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
  45         System.out.format( "[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n", 
  46                 label, 
  47                 humanReadableByteCount( memusage.getInit(), true ),
  48                 humanReadableByteCount( memusage.getUsed(), true ),
  49                 humanReadableByteCount( memusage.getCommitted(), true ),
  50                 freeratio * 100
  51         );
  52     }
  53 }