jdk/test/hotspot/jtreg/serviceability/jvmti/SuspendWithObjectMonitorWait/SuspendWithObjectMonitorWaitReentryPartFirst.java

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/*
 * @test
 * @bug 4413752 8262881
 * @summary Test SuspendThread with ObjectMonitor wait.
 * @requires vm.jvmti
 * @library /test/lib
 * @compile SuspendWithObjectMonitorWaitReentryPartFirst.java
 * @run main/othervm/native -agentlib:SuspendWithObjectMonitorWait SuspendWithObjectMonitorWaitReentryPartFirst 2
 */

import java.io.PrintStream;

//
// SuspendWithObjectMonitorWaitReentryPartFirst algorithm:
//
// main               waiter              resumer
// =================  ==================  ===================
// launch waiter
// <launch returns>   waiter running
// launch resumer     enter threadLock
// <launch returns>   threadLock.wait()   resumer running
// enter threadLock   :                   wait for notify
// threadLock.notify  wait finishes       :
// :                  reenter blocks      :
// suspend waiter     <suspended>         :
// <ready to test>    :                   :
// :                  :                   :
// notify resumer     :                   wait finishes
// delay 1-second     :                   :
// exit threadLock    :                   :
// join resumer       :                   enter threadLock
// :                  <resumed>           resume waiter
// :                  :                   exit threadLock
// :                  reenter threadLock  :
// <join returns>     :                   resumer exits
// join waiter        :
// <join returns>     waiter exits
//
// Note: The sleep(1-second) in main along with the delayed exit
//       of threadLock in main forces the resumer thread to reach
//       "enter threadLock" and block. This difference from the default scenario
//       forces the resumer thread to be contending for threadLock
//       while the waiter thread is in threadLock.wait() increasing
//       stress on the monitor sub-system.
//

public class SuspendWithObjectMonitorWaitReentryPartFirst extends SuspendWithObjectMonitorWaitBase {

    @Override
    public int run(int timeMax, PrintStream out) {
        return doWork2(timeMax, out);
    }

    // Notify the resumer while holding the threadLock.
    public int doWork2(int timeMax, PrintStream out) {
        SuspendWithObjectMonitorWaitWorker waiter;    // waiter thread
        SuspendWithObjectMonitorWaitWorker resumer;   // resumer thread

        System.out.println("Test 2: About to execute for " + timeMax + " seconds.");

        long start_time = System.currentTimeMillis();
        while (System.currentTimeMillis() < start_time + (timeMax * 1000)) {
            count++;
            testState = TS_INIT;  // starting the test loop

            // launch the waiter thread
            waiter = launchWaiter(0);

            // launch the resumer thread
            resumer = launchResumer(waiter);

            checkTestState(TS_RESUMER_RUNNING);

            // The waiter thread was synchronized on threadLock before it
            // set TS_WAITER_RUNNING and notified barrierLaunch above so
            // we cannot enter threadLock until the waiter thread calls
            // threadLock.wait().
            synchronized (threadLock) {
                // notify waiter thread so it can try to reenter threadLock
                testState = TS_READY_TO_NOTIFY;
                threadLock.notify();

                // wait for the waiter thread to block
                logDebug("before contended enter wait");
                int retCode = wait4ContendedEnter(waiter);
                if (retCode != 0) {
                    throw new RuntimeException("error in JVMTI GetThreadState: "
                            + "retCode=" + retCode);
                }
                logDebug("done contended enter wait");

                checkTestState(TS_READY_TO_NOTIFY);
                testState = TS_CALL_SUSPEND;
                logDebug("before suspend thread");
                retCode = suspendThread(waiter);
                if (retCode != 0) {
                    throw new RuntimeException("error in JVMTI SuspendThread: "
                            + "retCode=" + retCode);
                }
                logDebug("suspended thread");

                //
                // At this point, all of the child threads are running
                // and we can get to meat of the test:
                //
                // - suspended threadLock waiter (trying to reenter)
                // - a blocked threadLock enter in the resumer thread while the
                //   threadLock is held by the main thread.
                // - resumption of the waiter thread
                // - a threadLock enter in the freshly resumed waiter thread
                //
                barrierResumerNotify();
                try {
                    // Delay for 1-second while holding the threadLock to force the
                    // resumer thread to block on entering the threadLock.
                    Thread.sleep(1000);
                } catch (Exception e) {}
            }

            shutDown(waiter ,resumer);
            checkTestState(TS_WAITER_DONE);
        }

        System.out.println("Executed " + count + " loops in " + timeMax +
                " seconds.");

        return 0;
    }
}