test/jdk/java/util/concurrent/CompletableFuture/CompletableFutureOrTimeoutExceptionallyTest.java

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/*
 * @test
 * @bug 8303742
 * @summary CompletableFuture.orTimeout can leak memory if completed exceptionally
 * @modules java.base/java.util.concurrent:open
 * @run junit/othervm -Xmx128m CompletableFutureOrTimeoutExceptionallyTest
 */

import java.time.Duration;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;

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

class CompletableFutureOrTimeoutExceptionallyTest {
    // updated February 2025 to adapt to CompletableFuture DelayScheduler changes
    /**
     * Test that orTimeout task is cancelled if the CompletableFuture is completed Exceptionally
     */
    @Test
    void testOrTimeoutWithCompleteExceptionallyDoesNotLeak() throws InterruptedException {
        ForkJoinPool delayer = ForkJoinPool.commonPool();
        assertEquals(delayer.getDelayedTaskCount(), 0);
        var future = new CompletableFuture<>().orTimeout(12, TimeUnit.HOURS);
        future.completeExceptionally(new RuntimeException("This is fine"));
        while (delayer.getDelayedTaskCount() > 0) {
            Thread.sleep(100);
        };
    }

    /**
     * Test that the completeOnTimeout task is cancelled if the CompletableFuture is completed Exceptionally
     */
    @Test
    void testCompleteOnTimeoutWithCompleteExceptionallyDoesNotLeak() throws InterruptedException {
        ForkJoinPool delayer = ForkJoinPool.commonPool();
        assertEquals(delayer.getDelayedTaskCount(), 0);
        var future = new CompletableFuture<>().completeOnTimeout(null, 12, TimeUnit.HOURS);
        future.completeExceptionally(new RuntimeException("This is fine"));
        while (delayer.getDelayedTaskCount() > 0) {
            Thread.sleep(100);
        };
    }

}