Best approach to process batch API Request Lavel 5 - php

Question

EDIT : Already fixed the error Creating default object from empty value . My question now is just suggestions how to make this process better.
I am making a tool that sends batch API request to a certain URL. I am using https://github.com/stil/curl-easy for batch API request That API will validate the phone numbers I am sending and return a result. That API can support maximum 20 request per second, supposed I have 50,000 API request, what is the best and fastest way to process things?
The current process is, I query to my database for the number of records I have which is the number of phone numbers. Then I make a loop with the number of phone numbers. Inside a single iteration, I will query 13 records from the database then pass it to the queue and process it, when the processing is finished I will query again to the database and update the fields for the the phone number based on the API response. My problem is that I think I have a logic error on my loop when I run this the processing will stop for sometime and gives me:
Creating default object from empty value
I guess that is because of my loop here's my code.
public function getParallelApi()
{
$numItems = DB::connection('mysql')->select("SELECT COUNT(ID) AS cnt FROM phones WHERE status IS NULL");
for($y = 0; $y < $numItems[0]->cnt; $y++)
{
$queue = new \cURL\RequestsQueue;
// Set default options for all requests in queue
$queue->getDefaultOptions()
->set(CURLOPT_TIMEOUT, 5)
->set(CURLOPT_RETURNTRANSFER, true)
->set(CURLOPT_SSL_VERIFYPEER, false);
// This is the function that is called for every completed request
$queue->addListener('complete', function (\cURL\Event $event) {
$response = $event->response;
$json = $response->getContent(); // Returns content of response
$feed = json_decode($json, true);
$phone_number = $feed['msisdn'];
if(isset($phone_number))
{
$status = "";$remarks = "";$network = ""; $country = "";$country_prefix = "";
if(isset($feed['status']))
{
$status = $feed['status'];
}
if(isset($feed['network']))
{
$network = $feed['network'];
}
if(isset($feed['country']))
{
$country = $feed['country'];
}
if(isset($feed['country_prefix']))
{
$country_prefix = $feed['country_prefix'];
}
if(isset($feed['remark']))
{
$remarks = $feed['remark'];
}
$update = Phone::find($phone_number);
$update->network = $network;
$update->country = $country;
$update->country_prefix = $country_prefix;
$update->status = $status;
$update->remarks = $remarks;
$update->save();
}
});
// Get 13 records
$phone = DB::connection('mysql')->select("SELECT * FROM phones WHERE status IS NULL LIMIT 13");
foreach ($phone as $key => $value)
{
$request = new \cURL\Request($this->createCurlUrl($value->msisdn));
// var_dump($this->createCurlUrl($value->msisdn)); exit;
// Add request to queue
$queue->attach($request);
}
// Process the queue
while ($queue->socketPerform()) {
$queue->socketSelect();
}
sleep(2);
$y += 13; // Move to the next 13 records
}
Session::flash('alert-info', 'Data Updated Successfully!');
return Redirect::to('upload');
}
Since the maximum is 20 request per seconds I'm just doing it 13 request per second just to be sure I won't clog their server. I am adding sleep(2); to pause a bit so that I can make sure that the queue is fully processed before moving on.