func (c *Client) SendRequests(conn network.Connection, numRequests int, done func()) {
	go func() {
		wg := sync.WaitGroup{}

		interval := time.Duration((1.0 / float64(c.s.RPS)) * float64(time.Second))

		ticker := time.NewTicker(interval)
		for {
			// Wait for to send the next request.
			<-ticker.C

			// Send a request
			wg.Add(1)
			conn.Request(wg.Done)
			numRequests--

			if numRequests <= 0 {
				ticker.Stop()

func (db *DB) maybeOpenNewConnections() {
	numRequests := db.connRequests.Len()
	if db.maxOpen > 0 {
		numCanOpen := db.maxOpen - db.numOpen
		if numRequests > numCanOpen {
			numRequests = numCanOpen
		}
	}
	for numRequests > 0 {
		db.numOpen++ // optimistically
		numRequests--
		if db.closed {
			return
		}
		db.openerCh <- struct{}{}
	}
}

  const size_t block_size = 16;
  int num_requests = 0;
  Notification notification;
  auto fetcher = [&num_requests, &notification, block_size](
                     const string& filename, size_t offset, size_t n,
                     char* buffer, TF_Status* status) -> int64_t {
    EXPECT_EQ(n, block_size);
    EXPECT_EQ(offset, 0);
    num_requests++;
    memset(buffer, 'x', n);
    notification.Notify();