test/jdk/com/sun/management/OperatingSystemMXBean/GetProcessCpuTime.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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/*
 * @test
 * @bug     4858522
 * @summary Basic unit test of OperatingSystemMXBean.getProcessCpuTime()
 * @library /test/lib
 * @author  Steve Bohne
 */

/*
 * This test is just a sanity check and does not check for the correct
 * value.  The correct value should be checked manually:
 * Solaris/Linux:
 *   1. In a shell, enter the command: "ps -ef"
 *   2. The value (reported in seconds) is in the "TIME" column for the process
 * Windows NT/XP/2000:
 *   1. Hit Ctrl-Alt-Delete, select Task Manager, select Processes tab
 *   2. The value (reported in seconds) is in the "CPU Time" column for the
 *      process.  You may have to add this column via View menu-> Select
 *      Columns... item.
 * Windows 98/ME:
 *   Not supported.
 */

import com.sun.management.OperatingSystemMXBean;
import java.lang.management.*;
import jdk.test.lib.Platform;

public class GetProcessCpuTime {

    private static OperatingSystemMXBean mbean =
        (com.sun.management.OperatingSystemMXBean)
        ManagementFactory.getOperatingSystemMXBean();


    // Careful with these values.
    private static final long MIN_TIME_FOR_PASS = 1;
    private static final long MAX_TIME_FOR_PASS = Long.MAX_VALUE / 10_000_000;

    private static boolean trace = false;

    public static void main(String args[]) throws Exception {
        if (args.length > 0 && args[0].equals("trace")) {
            trace = true;
        }

        // Consume cpu time
        double sum=0;
        for (int i=0; i <=2000000; i++) {
          sum += i;
          sum /= i;
        }

        long ns = mbean.getProcessCpuTime();
        if (ns == -1 && Platform.isWindows()) {
            // Some Windows 2019 systems can return -1 for the first few reads.
            for (int i = 0; i < 10; i++) {
                ns = mbean.getProcessCpuTime();
                if (ns != -1) {
                    break;
                }
                try {
                    Thread.sleep(200);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
        if (ns == -1) {
            throw new RuntimeException("getProcessCpuTime() is not supported");
        }

        if (trace) {
            System.out.println("Process CPU time in ns: " + ns);
        }

        if (ns < MIN_TIME_FOR_PASS || ns > MAX_TIME_FOR_PASS) {
            throw new RuntimeException("Process CPU time " +
                                       "illegal value: " + ns + " ns " +
                                       "(MIN = " + MIN_TIME_FOR_PASS + "; " +
                                       "MAX = " + MAX_TIME_FOR_PASS + ")");
        }

        System.out.println("Test passed.");
    }
}