FindMonitorDeadlock.java

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/*
 * @test
 * @bug     4892507
 * @summary Basic Test for the following reset methods:
 *          - ThreadMXBean.findMonitorDeadlockedThreads()
 * @author  Mandy Chung
 *
 * @build MonitorDeadlock
 * @build ThreadDump
 * @run main/othervm FindMonitorDeadlock
 */

import java.lang.management.*;
import java.util.*;

public class FindMonitorDeadlock {
    public static void main(String[] argv) {
        // create deadlocked threads
        MonitorDeadlock md = new MonitorDeadlock();

        // No deadlock
        ThreadMXBean mbean = ManagementFactory.getThreadMXBean();
        long[] threads = mbean.findMonitorDeadlockedThreads();
        if (threads != null) {
            throw new RuntimeException("TEST FAILED: Should return null.");
        }

        // Let the threads to proceed
        md.goDeadlock();

        // wait until the deadlock is ready
        md.waitUntilDeadlock();

        // Find Deadlock
        threads = mbean.findMonitorDeadlockedThreads();
        if (threads == null) {
            ThreadDump.dumpStacks();
            throw new RuntimeException("TEST FAILED: Deadlock not detected.");
        }

        // Print Deadlock stack trace
        System.out.println("Found threads that are in deadlock:-");
        ThreadInfo[] infos = mbean.getThreadInfo(threads, Integer.MAX_VALUE);
        for (int i = 0; i < infos.length; i++) {
            ThreadDump.printThreadInfo(infos[i]);
        }

        md.checkResult(threads);
        System.out.println("Test passed");
    }
}