"Error while attempting to shut down the service after failure.",
                    ignored);
          }
          notifyFailed(t);
          // requireNonNull is safe now, just as it was above.
          requireNonNull(runningTask).cancel(false); // prevent future invocations.
        } finally {
          lock.unlock();
        }
      }
    }

            //
            // If we were to cancel taskFuture, that would let the next task start while the old
            // one is still running.
            //
            // Now, maybe we could tweak our implementation to not start the next task until the
            // callable actually completes. (We could detect completion in our wrapper

    if (javaVersion != null && javaVersion >= 9) {
      return;
    }
    // Obviously this isn't guaranteed in every environment, but it works well enough for now:
    assertTrue(lazyStackTraceIsLazy());
  }

  @J2ktIncompatible
  @GwtIncompatible // lazyStackTrace(Throwable)
  public void testLazyStackTrace() {
    Exception e = new Exception();

    if (javaVersion != null && javaVersion >= 9) {
      return;
    }
    // Obviously this isn't guaranteed in every environment, but it works well enough for now:
    assertTrue(lazyStackTraceIsLazy());
  }

  @J2ktIncompatible
  @GwtIncompatible // lazyStackTrace(Throwable)
  public void testLazyStackTrace() {
    Exception e = new Exception();

                  created = true;
                }
              } finally {
                busy = 0;
              }
              if (created) break;
              continue; // Slot is now non-empty
            }
          }
          collide = false;
        } else if (!wasUncontended) // CAS already known to fail
        wasUncontended = true; // Continue after rehash

      long minDeltaOrZero = delta & (delta >> (Long.SIZE - 1));
      // equivalent to Math.min(delta, 0)

      a = delta - minDeltaOrZero - minDeltaOrZero; // sets a to Math.abs(a - b)
      // a is now nonnegative and even

      b += minDeltaOrZero; // sets b to min(old a, b)
      a >>= Long.numberOfTrailingZeros(a); // divide out all 2s, since 2 doesn't divide b
    }
    return a << min(aTwos, bTwos);
  }

    }

    /*
     * TODO(cpovirk): `return (V) removedValue` once our checker permits that.
     *
     * (We promoted a class of warnings into errors because sometimes they indicate real problems.
     * But now we need to "undo" some instance of spurious errors, as discussed in
     * https://github.com/jspecify/checker-framework/issues/8.)
     */
    return removedValue == null ? null : (V) removedValue;
  }

  @Override

      fail();
    } catch (IllegalStateException expected) {
    }
  }

  // Technically we should test other reentrant scenarios (9 combinations of
  // hasNext/next/peek), but we'll cop out for now, knowing that peek() and
  // next() both start by invoking hasNext() anyway.

  /** Throws an undeclared checked exception. */
  private static void sneakyThrow(Throwable t) {

    f1.cancel(true);
    assertTrue(f2.isCancelled());
    /*
     * We might like to propagate interruption, too, but it's not clear that it matters. For now, we
     * test for the behavior that we have today.
     */
    assertFalse(((AbstractFuture<?>) f2).wasInterrupted());
  }

  /*

  private static <K, V> int countLiveEntries(LocalCache<K, V> map, long now) {
    int result = 0;
    for (Segment<K, V> segment : map.segments) {
      AtomicReferenceArray<ReferenceEntry<K, V>> table = segment.table;
      for (int i = 0; i < table.length(); i++) {
        for (ReferenceEntry<K, V> e = table.get(i); e != null; e = e.getNext()) {
          if (map.isLive(e, now)) {
            result++;
          }
        }