test/jdk/java/lang/Thread/virtual/ThreadPollOnYield.java

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/*
 * @test id=default
 * @bug 8335269
 * @summary Test that Thread.yield loop polls for safepoints
 * @requires vm.continuations
 * @library /test/lib
 * @run junit/othervm/native --enable-native-access=ALL-UNNAMED ThreadPollOnYield
 */

/*
 * @test id=c2
 * @bug 8335269
 * @summary Test that Thread.yield loop polls for safepoints
 * @requires vm.continuations & vm.compMode != "Xcomp"
 * @library /test/lib
 * @run junit/othervm/native --enable-native-access=ALL-UNNAMED -Xcomp -XX:-TieredCompilation
 *                           -XX:CompileCommand=inline,*::yield* -XX:CompileCommand=inline,*::*Yield ThreadPollOnYield
 */

import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.CountDownLatch;

import jdk.test.lib.thread.VThreadPinner;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

class ThreadPollOnYield {
    private static final CountDownLatch started = new CountDownLatch(1);
    static void foo(AtomicBoolean done) {
        started.countDown();
        while (!done.get()) {
            Thread.yield();
        }
    }

    @Test
    void testThreadYieldPolls() throws Exception {
        AtomicBoolean done = new AtomicBoolean();
        var vthread = Thread.ofVirtual().start(() -> {
            VThreadPinner.runPinned(() -> foo(done));
        });
        started.await();
        done.set(true);
        vthread.join();

        System.out.println("First vthread done");

        AtomicBoolean done2 = new AtomicBoolean();
        vthread = Thread.ofVirtual().start(() -> {
            VThreadPinner.runPinned(() -> foo(done2));
        });
        long start = System.currentTimeMillis();
        while (System.currentTimeMillis() - start < 5000) {
            Thread.sleep(250);
            System.gc();
        }
        done2.set(true);
        vthread.join();
    }
}