jdk-24/test/hotspot/jtreg/serviceability/jvmti/vthread/ThreadStateTest/ThreadStateTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 2 along with this work; if not, write to the Free Software Foundation,
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/**
 * @test
 * @bug 8307365
 * @summary Exercise JvmtiThreadState creation concurrently with terminating vthreads
 * @requires vm.continuations
 * @modules java.base/java.lang:+open
 * @run main/othervm/native -agentlib:ThreadStateTest ThreadStateTest
 */

import java.util.concurrent.*;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.List;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

public class ThreadStateTest {
    static final int VTHREAD_COUNT = 64;

    private static native void setSingleSteppingMode(boolean enable);
    private static native void setMonitorContendedMode(boolean enable);

    final Runnable FOO = () -> {
        Thread.yield();
    };

    private void runTest() throws Exception {
        int tryCount = 150;

        // Force creation of JvmtiThreadState on vthread start.
        setMonitorContendedMode(true);

        while (tryCount-- > 0) {
            ExecutorService scheduler = Executors.newFixedThreadPool(8);
            ThreadFactory factory = virtualThreadBuilder(scheduler).factory();

            List<Thread> virtualThreads = new ArrayList<>();
            for (int i = 0; i < VTHREAD_COUNT; i++) {
                virtualThreads.add(factory.newThread(FOO));
            }

            for (Thread t : virtualThreads) {
                t.start();
            }

            // Give some time for vthreads to finish.
            Thread.sleep(10);

            // Trigger race of JvmtiThreadState creation with terminating vthreads.
            setMonitorContendedMode(false);
            setMonitorContendedMode(true);

            for (Thread t : virtualThreads) {
                t.join();
            }
            // Let all carriers go away.
            scheduler.shutdown();
            Thread.sleep(20);

            // Check that looping over all JvmtiThreadStates works fine.
            setSingleSteppingMode(true);

            // Reset for next iteration
            setSingleSteppingMode(false);
        }
    }

    public static void main(String[] args) throws Exception {
        ThreadStateTest obj = new ThreadStateTest();
        obj.runTest();
    }

    private static Thread.Builder.OfVirtual virtualThreadBuilder(Executor scheduler) {
        Thread.Builder.OfVirtual builder = Thread.ofVirtual();
        try {
            Class<?> clazz = Class.forName("java.lang.ThreadBuilders$VirtualThreadBuilder");
            Constructor<?> ctor = clazz.getDeclaredConstructor(Executor.class);
            ctor.setAccessible(true);
            return (Thread.Builder.OfVirtual) ctor.newInstance(scheduler);
        } catch (InvocationTargetException e) {
            Throwable cause = e.getCause();
            if (cause instanceof RuntimeException re) {
                throw re;
            }
            throw new RuntimeException(e);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}