Блокировка базы данных при попытке сохранить данные в нескольких таблицах

Я разработал приложение для обработки заказов, когда несколько человек пытаются забронировать номера.
До сих пор все было хорошо, но по мере того, как трафик увеличивался на 100-200, приложение сразу переходило в тупик дБ.

Ошибка:

Deadlock found when trying to get lock; try restarting transaction
INSERT INTO `booking_passenger_map` (`booking_id`, `passenger_id`) VALUES (7665, 18111)

Код:

$this->db->trans_start();
if(isset($user["booking_id"]))
{
$bd=$this->common->getBookingById($user["booking_id"]);
if($bd[0]->booking_status_id!=CONFIRM && $bd[0]->booking_status_id!=PAID_BUT_WAITING)
{
$booking_id=$user["booking_id"];
$this->common->deleteBooking($booking_id);
}
}
$booking_id=$this->common->saveBooking($data);
//End Create Booking

//Saving Passengers
for($i=1; $i<=count($passengers); $i++)
{
$passenger_id=$this->common->savePassenger($passengers["pass_".$i]);
//Booking Passenger Map
$bpm["booking_id"]=$booking_id;
$bpm["passenger_id"]=$passenger_id;
$this->common->saveBookingPassMap($bpm);
}
//End Saving Passengers

//Creating Booking Room Map
foreach($cart AS $detail)
{
if(in_array($detail["cat"]->id, $this->config->item("dmtry")))
{
$no_of_beds = $detail[$detail["deck"]->id]["num_of_beds"];
$needed_beds=$this->common->getNeededDmtryCatDataById($detail["cat"]->id, $sf["schedule_id"], $no_of_beds);
if(count($needed_beds)<$no_of_beds)
{
$this->session->set_flashdata('msg',
"<div class='alert alert-success'>Sorry, Somebody else was more quick in booking the beds from dormetry you
are trying. No worries we have more options for you</div>");
redirect(base_url()."booking/show_rooms");
}
else
{
foreach($needed_beds AS $needed_bed){
$brm["booking_id"]=$booking_id;
$brm["category_id"]=$detail["cat"]->id;
$brm["room_id"]=$needed_bed->r_id;
$brm["bunk_id"]=$needed_bed->b_id;
$brm["no_of_ppl"]=1;
$brm["room_capacity"]=$detail["cat"]->capacity;
$brm["b_adult_rate"]=$detail["rate"]->adult_rate;
$brm["b_child_rate"]=$detail["rate"]->child_rate;
$brm["b_infant_rate"]=$detail["rate"]->infant_rate;
$this->common->saveBookingRoomMap($brm);
}
}
}
else
{
$no_of_rooms = $detail[$detail["deck"]->id]["num_of_rooms"];
$needed_rooms=$this->common->getNeededRoomCatDataById($detail["cat"]->id, $sf["schedule_id"], $no_of_rooms);
if(count($needed_rooms)<$no_of_rooms)
{
$this->session->set_flashdata('msg',
"<div class='alert alert-success'>Sorry, Somebody else was more quick in booking the rooms you
are trying. No worries we have more options for you</div>");
redirect(base_url()."booking/show_rooms");
}
else
{
$temp_ppl=$detail["ppl"];
foreach($needed_rooms AS $needed_room){
if($temp_ppl>=$detail["cat"]->capacity){
$no_of_ppl=$detail["cat"]->capacity;
}
else if($temp_ppl<$detail["cat"]->capacity){
$no_of_ppl=$temp_ppl;
}
if($no_of_ppl<$detail["cat"]->capacity){
$empty_beds=$detail["cat"]->capacity-$no_of_ppl;
}
if($empty_beds)
{
$brm["extra_percent"]=EXTRA;
}
$brm["booking_id"]=$booking_id;
$brm["category_id"]=$detail["cat"]->id;
$brm["room_id"]=$needed_room->r_id;
$brm["bunk_id"]=0;
$brm["no_of_ppl"]=$no_of_ppl;
$brm["room_capacity"]=$detail["cat"]->capacity;
$brm["b_adult_rate"]=$detail["rate"]->adult_rate;
$brm["b_child_rate"]=$detail["rate"]->child_rate;
$brm["b_infant_rate"]=$detail["rate"]->infant_rate;
$this->common->saveBookingRoomMap($brm);

$temp_ppl-=$no_of_ppl;
}
}
}
}

$this->db->trans_complete();

//End Creating Booking Room Map
if($this->isTransSuccess())
{
$user["booking_id"]=$booking_id;
$this->session->set_userdata('key_user', $user);
$cca_data=$this->getCCAData($data["amount_paid"]);
$back_user=$this->session->userdata("back_user");
if($back_user!=null && $back_user->user_role_id==ADMIN)
$this->confirmWithoutPayment();
else
$this->ccavenue->pay($cca_data);
exit;
}
else
redirect(base_url()."booking/cart");

Я проделал большую работу вокруг, а также попытался изменить порядок вставки, но ничего не получилось. Пожалуйста, ознакомьтесь с кодом и помогите, что очень много значит для меня.