min := 15
		for {
			m := multiples(<-primes)
			head := <-m
			for min < head {
				composites <- min
				minchan := heap.Pop(&h).(*PeekCh)
				min = minchan.head
				minchan.head = <-minchan.ch
				heap.Push(&h, minchan)
			}
			for min == head {
				minchan := heap.Pop(&h).(*PeekCh)
				min = minchan.head
				minchan.head = <-minchan.ch
				heap.Push(&h, minchan)
			}
			composites <- head

	}
	for {
		old := atomic.Load64((*uint64)(head))
		node.next = old
		if atomic.Cas64((*uint64)(head), old, new) {
			break
		}
	}
}

func (head *lfstack) pop() unsafe.Pointer {
	for {
		old := atomic.Load64((*uint64)(head))
		if old == 0 {
			return nil
		}
		node := lfstackUnpack(old)
		next := atomic.Load64(&node.next)
		if atomic.Cas64((*uint64)(head), old, next) {
			return unsafe.Pointer(node)
		}

		select {
		case d.execute <- t:
			return true
		case <-stop:
			return false
		}
	}

	for {
		var task *delayTask
		d.mu.Lock()
		if head := d.queue.Peek(); head != nil {
			task = head.(*delayTask)
			heap.Pop(d.queue)
		}
		d.mu.Unlock()

		if task != nil {
			delay := time.Until(task.runAt)
			if delay <= 0 {

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	heap[len(heap)-1].ev.time = 21
	heapUpdate(heap, len(heap)-1)
	checkHeap(t, heap)
	if heap[len(heap)-1].ev.time != 21 {
		t.Fatalf("heap update failed, expected %d as heap min: %s", 21, heapDebugString(heap))
	}

	// Update the last element to be smaller.
	heap[len(heap)-1].ev.time = 7
	heapUpdate(heap, len(heap)-1)
	checkHeap(t, heap)
	if heap[len(heap)-1].ev.time == 21 {

	type X struct {
		buf     [1]byte
		nextbuf []byte
		next    *X
	}
	var head *X
	for i := 0; i < 10; i++ {
		p := &X{}
		p.buf[0] = 42
		p.next = head
		if head != nil {
			p.nextbuf = head.buf[:]
		}
		head = p
		runtime.GC()
	}
	for p := head; p != nil; p = p.next {
		if p.buf[0] != 42 {
			t.Fatal("corrupted heap")
		}
	}
}

func TestGcRescan(t *testing.T) {
	type X struct {

func (q *UniqueQueue) Replace(value TimedValue) bool {
	q.lock.Lock()
	defer q.lock.Unlock()

	for i := range q.queue {
		if q.queue[i].Value != value.Value {
			continue
		}
		heap.Remove(&q.queue, i)
		heap.Push(&q.queue, &value)
		return true
	}
	return false
}

// RemoveFromQueue the value from the queue, but keeps it in the set,
// so it won't be added second time. Returns true if something was
// removed.

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// - Maps and channels contains no-in-heap types are disallowed.
//
// 4. Write barriers on pointers to not-in-heap types can be omitted.
//
// The last point is the real benefit of NotInHeap. The runtime uses
// it for low-level internal structures to avoid memory barriers in the
// scheduler and the memory allocator where they are illegal or simply