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

func listPathRaw(ctx context.Context, opts listPathRawOptions) (err error) {
	disks := opts.disks
	if len(disks) == 0 {
		return fmt.Errorf("listPathRaw: 0 drives provided")
	}

	// Cancel upstream if we finish before we expect.
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	// Keep track of fallback disks
	var fdMu sync.Mutex
	fds := opts.fallbackDisks
	fallback := func(err error) StorageAPI {

and walking away.  `You insult me by talking such nonsense!'

  `I didn't mean it!' pleaded poor Alice.  `But you're so easily
offended, you know!'

  The Mouse only growled in reply.

  `Please come back and finish your story!' Alice called after
it; and the others all joined in chorus, `Yes, please do!' but
the Mouse only shook its head impatiently, and walked a little
quicker.

    // 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");

    // 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

    [ObsoleteApacheClient.java][obsolete_apache_client] into your project.

 *  **OkHttp now supports duplex calls over HTTP/2.** With normal HTTP calls the request must finish
    before the response starts. With duplex, request and response bodies are transmitted
    simultaneously. This can be used to implement interactive conversations within a single HTTP
    call.