g.Go(func() error {
			if formats[index] == nil {
				return errDiskNotFound
			}
			return saveFormatErasure(storageDisks[index], formats[index], "")
		}, index)
	}

	// Wait for the routines to finish.
	return reduceWriteQuorumErrs(ctx, g.Wait(), nil, len(storageDisks))
}

// relinquishes the underlying connection for all storage disks.
func closeStorageDisks(storageDisks ...StorageAPI) {
	var wg sync.WaitGroup

      Executor executor) {
    return AbstractCatchingFuture.createAsync(input, exceptionType, fallback, executor);
  }

  /**
   * Returns a future that delegates to another but will finish early (via a {@link
   * TimeoutException} wrapped in an {@link ExecutionException}) if the specified duration expires.
   *
   * <p>The delegate future is interrupted and cancelled if it times out.
   *

    // give the third get a chance to run; it is okay for this to be racy
    // as the end result should be the same either way
    fourthSignal.await();
    Thread.yield();

    // let computation finish
    computeSignal.countDown();
    doneSignal.await();

    assertThat(callCount.get()).isEqualTo(1);
    assertThat(result.get(0)).isEqualTo("barfoo");
    assertThat(result.get(1)).isEqualTo("barfoo");

know your history, she do.'

  `I'll tell it her,' said the Mock Turtle in a deep, hollow
tone:  `sit down, both of you, and don't speak a word till I've
finished.'

  So they sat down, and nobody spoke for some minutes.  Alice
thought to herself, `I don't see how he can EVEN finish, if he
doesn't begin.'  But she waited patiently.

  `Once,' said the Mock Turtle at last, with a deep sigh, `I was
a real Turtle.'

    // give the third get a chance to run; it is okay for this to be racy
    // as the end result should be the same either way
    fourthSignal.await();
    Thread.yield();

    // let computation finish
    computeSignal.countDown();
    doneSignal.await();

    assertThat(callCount.get()).isEqualTo(1);
    assertThat(result.get(0)).isEqualTo("barfoo");
    assertThat(result.get(1)).isEqualTo("barfoo");

Worse, there is no guarantee that the write to <code>done</code> will ever
be observed by <code>main</code>, since there are no synchronization
events between the two threads.  The loop in <code>main</code> is not
guaranteed to finish.
</p>

<p>
There are subtler variants on this theme, such as this program.
</p>

<pre>
type T struct {
	msg string
}

var g *T

func setup() {
	t := new(T)

   * computes or retrieves it using the supplied {@code CacheLoader}. If another thread is currently
   * loading the value for this key, simply waits for that thread to finish and returns its loaded
   * value. Note that multiple threads can concurrently load values for distinct keys.
   *
   * <p>This method does not alter the state of this {@code CacheBuilder} instance, so it can be

			if disks[index] == nil {
				return errDiskNotFound
			}
			return disks[index].RenamePart(ctx, srcBucket, srcEntry, dstBucket, dstEntry, optsMeta, skipParent)
		}, index)
	}

	// Wait for all renames to finish.
	errs := g.Wait()

	err := reduceWriteQuorumErrs(ctx, errs, objectOpIgnoredErrs, writeQuorum)
	if err != nil {
		er.cleanupMultipartPath(ctx, paths...)
	}

   * computes or retrieves it using the supplied {@code CacheLoader}. If another thread is currently
   * loading the value for this key, simply waits for that thread to finish and returns its loaded
   * value. Note that multiple threads can concurrently load values for distinct keys.
   *
   * <p>This method does not alter the state of this {@code CacheBuilder} instance, so it can be

    peer.play()

    // Play it back.
    val connection = connect(peer)
    connection.writePingAndAwaitPong()
    val stream = connection.newStream(headerEntries("a", "android"), true)
    // finish the stream
    stream.writeHeaders(headerEntries("b", "berserk"), true, false)
    assertFailsWith<IllegalStateException> {
      stream.enqueueTrailers(headersOf("trailers", "boom"))
    }
  }