java8 乱序_为什么Java 8 CompletableFuture thenCompose会根据完成顺序生成不同的异常？...

我遇到过

Java 8 CompletableFuture thenCompose方法的奇怪行为.我有两个测试,仅在执行顺序上有所不同.两个测试都模拟thenCompose中生成的CompletableFuture中的失败.

@Test

public void completedAfter() {

CompletableFuture future1 = new CompletableFuture<>();

CompletableFuture future2 = new CompletableFuture<>();

future1.thenCompose(x -> future2).whenComplete((r, e) -> System.out.println("After: " + e));

future1.complete("value");

future2.completeExceptionally(new RuntimeException());

}

@Test

public void completedBefore() {

CompletableFuture future1 = new CompletableFuture<>();

CompletableFuture future2 = new CompletableFuture<>();

future1.complete("value");

future2.completeExceptionally(new RuntimeException());

future1.thenCompose(x -> future2).whenComplete((r, e) -> System.out.println("Before: " +e));

}

输出是：

After: java.util.concurrent.CompletionException: java.lang.RuntimeException

Before: java.lang.RuntimeException

问题是,为什么在一个案例中包含在CompletionException中但在另一个案例中却没有包含异常？

更新：Here是相关的错误报告.它已被标记并解析为JDK中的错误.