GetSystemLoadAverage.java revision 5116:d45bc4307996 
1/*
2 * Copyright (c) 2005, 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/*
25 *
26 *
27 * @bug     6336608 6511738
28 * @summary Basic unit test of OperatingSystemMXBean.getSystemLoadAverage()
29 * @author  Mandy Chung
30 */
31
32/*
33 * This test tests the load average on linux and solaris. On Windows,
34 * getSystemLoadAverage() returns -1.
35 *
36 * Usage: GetSystemLoadAverage ["-1.0"]
37 * Arguments:
38 *   o If no argument is specified, the test will verify the system load
39 *     average with the /usr/bin/uptime command.
40 *   o Otherwise, the input argument must be "-1.0" indicating the
41 *     expected system load average.  This would only be the case when
42 *     running on Windows.
43 */
44
45import java.lang.management.*;
46import java.io.*;
47
48public class GetSystemLoadAverage {
49
50    private static OperatingSystemMXBean mbean =
51        ManagementFactory.getOperatingSystemMXBean();
52
53    // The system load average may be changing due to other jobs running.
54    // Allow some delta.
55    private static double DELTA = 0.05;
56
57    public static void main(String args[]) throws Exception {
58        if (args.length > 1)  {
59            throw new IllegalArgumentException("Unexpected number of args " + args.length);
60        }
61
62        if (args.length == 0) {
63            // On Linux or Solaris
64            checkLoadAvg();
65        } else {
66            // On Windows, the system load average is expected to be -1.0
67            if (!args[0].equals("-1.0")) {
68                throw new IllegalArgumentException("Invalid argument: " + args[0]);
69            } else {
70                double loadavg = mbean.getSystemLoadAverage();
71                if (loadavg != -1.0) {
72                    throw new RuntimeException("Expected load average : -1.0" +
73                        " but getSystemLoadAverage returned: " +
74                        loadavg);
75                }
76            }
77        }
78
79        System.out.println("Test passed.");
80    }
81
82    private static String LOAD_AVERAGE_TEXT
83            = System.getProperty("os.name").startsWith("Mac OS")
84                ? "load averages:"
85                : "load average:";
86
87    private static void checkLoadAvg() throws Exception {
88        // Obtain load average from OS command
89        ProcessBuilder pb = new ProcessBuilder("/usr/bin/uptime");
90        Process p = pb.start();
91        String output = commandOutput(p);
92
93        // obtain load average from OperatingSystemMXBean
94        double loadavg = mbean.getSystemLoadAverage();
95
96        // verify if two values are close
97        output = output.substring(output.lastIndexOf(LOAD_AVERAGE_TEXT) +
98                                  LOAD_AVERAGE_TEXT.length() + 1);
99        System.out.println("Load average returned from uptime = " + output);
100        System.out.println("getSystemLoadAverage() returned " + loadavg);
101
102        String[] lavg = System.getProperty("os.name").startsWith("Mac OS")
103                ? output.split(" ")
104                : output.split(",");
105        double expected = Double.parseDouble(lavg[0]);
106        double lowRange = expected * (1 - DELTA);
107        double highRange = expected * (1 + DELTA);
108
109        if (loadavg < lowRange || loadavg >  highRange) {
110            throw new RuntimeException("Expected load average : " +
111                    expected +
112                    " but getSystemLoadAverage returned: " +
113                    loadavg);
114        }
115    }
116
117    private static String commandOutput(Reader r) throws Exception {
118        StringBuilder sb = new StringBuilder();
119        int c;
120        while ((c = r.read()) > 0) {
121            if (c != '\r') {
122                sb.append((char) c);
123            }
124        }
125        return sb.toString();
126    }
127
128    private static String commandOutput(Process p) throws Exception {
129        Reader r = new InputStreamReader(p.getInputStream(),"UTF-8");
130        String output = commandOutput(r);
131        p.waitFor();
132        p.exitValue();
133        return output;
134    }
135
136}
137