// allocate a new arena.
	lock(&gcBitsArenas.lock)
	// Try the head arena again, since it may have changed. Now
	// that we hold the lock, the list head can't change, but its
	// free position still can.
	if p := gcBitsArenas.next.tryAlloc(bytesNeeded); p != nil {
		unlock(&gcBitsArenas.lock)
		return p
	}

	// Allocate a new arena. This may temporarily drop the lock.
	fresh := newArenaMayUnlock()

func (p *PriorityQueue) Close() {
	p.lock.Lock()
	defer p.lock.Unlock()
	close(p.stop)
	p.closed = true
	p.cond.Broadcast()
}

// DeleteNominatedPodIfExists deletes <pod> from nominatedPods.
func (npm *nominator) DeleteNominatedPodIfExists(pod *v1.Pod) {
	npm.lock.Lock()
	npm.deleteNominatedPodIfExistsUnlocked(pod)
	npm.lock.Unlock()
}

func (plugin *FakeVolumePlugin) NewMounter(spec *volume.Spec, pod *v1.Pod, opts volume.VolumeOptions) (volume.Mounter, error) {
	plugin.Lock()
	defer plugin.Unlock()
	if spec.Name() == FailNewMounter {
		return nil, fmt.Errorf("AlwaysFailNewMounter")
	}
	fakeVolume := plugin.getFakeVolume(&plugin.Mounters)
	fakeVolume.Lock()
	defer fakeVolume.Unlock()
	fakeVolume.PodUID = pod.UID
	fakeVolume.VolName = spec.Name()
	fakeVolume.Plugin = plugin

   * cancelled without a call to {@code cancel}, such as by calling {@code
   * setFuture(cancelledFuture)}.
   *
   * <p>Beware of completing a future while holding a lock. Its listeners may do slow work or
   * acquire other locks, risking deadlocks.
   */
  @CanIgnoreReturnValue
  @Override
  public boolean cancel(boolean mayInterruptIfRunning) {
    Object localValue = value;
    boolean rValue = false;

   * cancelled without a call to {@code cancel}, such as by calling {@code
   * setFuture(cancelledFuture)}.
   *
   * <p>Beware of completing a future while holding a lock. Its listeners may do slow work or
   * acquire other locks, risking deadlocks.
   */
  @CanIgnoreReturnValue
  @Override
  public boolean cancel(boolean mayInterruptIfRunning) {
    Object localValue = value;
    boolean rValue = false;

}

func (c *Cacher) startCaching(stopChannel <-chan struct{}) {
	// The 'usable' lock is always 'RLock'able when it is safe to use the cache.
	// It is safe to use the cache after a successful list until a disconnection.
	// We start with usable (write) locked. The below OnReplace function will
	// unlock it after a successful list. The below defer will then re-lock
	// it when this function exits (always due to disconnection), only if

	// huge pages. We'll set all the old entries after we release the lock.
	lock(&h.lock)
	if h.arenasHugePages {
		unlock(&h.lock)
		return
	}
	h.arenasHugePages = true
	unlock(&h.lock)

	// N.B. The arenas L1 map is quite small on all platforms, so it's fine to
	// just iterate over the whole thing.
	for i := range h.arenas {

   * of reads may not be immediately reflected on the algorithm's data structures. These structures
   * are guarded by a lock and operations are applied in batches to avoid lock contention. The
   * penalty of applying the batches is spread across threads so that the amortized cost is slightly
   * higher than performing just the operation without enforcing the capacity constraint.

// It prevents data being changed after retrieving it from the map.
func (n *nodeHealthMap) getDeepCopy(name string) *nodeHealthData {
	n.lock.RLock()
	defer n.lock.RUnlock()
	return n.nodeHealths[name].deepCopy()
}

func (n *nodeHealthMap) set(name string, data *nodeHealthData) {
	n.lock.Lock()
	defer n.lock.Unlock()
	n.nodeHealths[name] = data
}

type podUpdateItem struct {
	namespace string
	name      string
}

	mheap_.reclaimIndex.Store(0)
	mheap_.reclaimCredit.Store(0)
	unlock(&mheap_.lock)

	sweep.centralIndex.clear()

	if !concurrentSweep || mode == gcForceBlockMode {
		// Special case synchronous sweep.
		// Record that no proportional sweeping has to happen.
		lock(&mheap_.lock)
		mheap_.sweepPagesPerByte = 0
		unlock(&mheap_.lock)
		// Flush all mcaches.
		for _, pp := range allp {