jdk-24/test/jdk/java/lang/Thread/virtual/VirtualThreadPinnedEventThrows.java

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/**
 * @test
 * @summary Test parking when pinned and emitting the JFR VirtualThreadPinnedEvent throws
 * @modules java.base/jdk.internal.event
 * @compile/module=java.base jdk/internal/event/VirtualThreadPinnedEvent.java
 * @run junit VirtualThreadPinnedEventThrows
 */

import java.lang.ref.Reference;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.LockSupport;
import jdk.internal.event.VirtualThreadPinnedEvent;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

class VirtualThreadPinnedEventThrows {

    /**
     * Test parking when pinned and creating the VirtualThreadPinnedEvent fails with OOME.
     */
    @Test
    void testVirtualThreadPinnedEventCreateThrows() throws Exception {
        VirtualThreadPinnedEvent.setCreateThrows(true);
        try {
            testParkWhenPinned();
        } finally {
            VirtualThreadPinnedEvent.setCreateThrows(false);
        }
    }

    /**
     * Test parking when pinned and VirtualThreadPinnedEvent.begin fails with OOME.
     */
    @Test
    void testVirtualThreadPinnedEventBeginThrows() throws Exception {
        VirtualThreadPinnedEvent.setBeginThrows(true);
        try {
            testParkWhenPinned();
        } finally {
            VirtualThreadPinnedEvent.setBeginThrows(false);
        }
    }

    /**
     * Test parking when pinned and VirtualThreadPinnedEvent.commit fails with OOME.
     */
    @Test
    void testVirtualThreadPinnedEventCommitThrows() throws Exception {
        VirtualThreadPinnedEvent.setCommitThrows(true);
        try {
            testParkWhenPinned();
        } finally {
            VirtualThreadPinnedEvent.setCommitThrows(false);
        }
    }

    /**
     * Test parking a virtual thread when pinned.
     */
    private void testParkWhenPinned() throws Exception {
        Object lock = new Object();
        try {
            var completed = new AtomicBoolean();
            Thread thread = Thread.startVirtualThread(() -> {
                synchronized (lock) {
                    LockSupport.park();
                    completed.set(true);
                }
            });

            // wait for thread to park
            Thread.State state;
            while ((state = thread.getState()) != Thread.State.WAITING) {
                assertTrue(state != Thread.State.TERMINATED);
                Thread.sleep(10);
            }

            // unpark and check that thread completed without exception
            LockSupport.unpark(thread);
            thread.join();
            assertTrue(completed.get());
        } finally {
            Reference.reachabilityFence(lock);
        }
    }
}