test/sun/management/HotspotThreadMBean/GetInternalThreads.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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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     4530538
 * @summary Basic Test for HotspotThreadMBean.getInternalThreadCount()
 *          and getInternalThreadCpuTime()
 * @author  Mandy Chung
 */

import sun.management.*;
import java.util.*;
import java.lang.management.ThreadMXBean;
import java.lang.management.ManagementFactory;

public class GetInternalThreads {
    private static HotspotThreadMBean mbean =
        ManagementFactoryHelper.getHotspotThreadMBean();

    // Minimum number of VM internal threads
    //   VM thread, watcher thread, Low memory detector, compiler thread
    private static final long MIN_VALUE_FOR_PASS = 4;
    private static final long MAX_VALUE_FOR_PASS = Long.MAX_VALUE;

    public static void main(String[] args) {
        long value = mbean.getInternalThreadCount();

        if (value < MIN_VALUE_FOR_PASS || value > MAX_VALUE_FOR_PASS) {
            throw new RuntimeException("Internal thread count " +
                                       "illegal value: " + value + " " +
                                       "(MIN = " + MIN_VALUE_FOR_PASS + "; " +
                                       "MAX = " + MAX_VALUE_FOR_PASS + ")");
        }

        System.out.println("Internal Thread Count = " + value);

        ThreadMXBean thread =
            ManagementFactory.getThreadMXBean();
        if (!thread.isThreadCpuTimeSupported()) {
            System.out.println("Thread Cpu Time is not supported.");
            return;
        }

        Map times = mbean.getInternalThreadCpuTimes();
        Iterator iter = times.entrySet().iterator();
        for (; iter.hasNext(); ) {
            Map.Entry entry = (Map.Entry) iter.next();
            System.out.println(entry.getKey() +
                " CPU time = " + entry.getValue() + "ns");
            if (((Long) entry.getValue()).longValue() < 0) {
                throw new RuntimeException("Thread CPU time" +
                    "illegal value: " + entry.getValue());
            }
        }
        System.out.println("Test passed.");
    }
}