需要帮助解决死锁并了解导致死锁的原因吗
表格：

CREATE TABLE `payments` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `billing_id` int(10) unsigned NOT NULL,
  `foreign_transaction_id` varchar(255) NOT NULL,
  `product_type` enum('invoice') DEFAULT NULL,
  `product_id` int(10) unsigned DEFAULT NULL,
  `subscription_id` int(10) unsigned DEFAULT NULL,
  `credit_id` int(10) unsigned DEFAULT NULL,
  `time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `type` enum('payment') DEFAULT NULL,
  `amount` decimal(8,2) NOT NULL DEFAULT '0.00',
  `fee` decimal(8,2) NOT NULL DEFAULT '0.00',
  `vat` decimal(8,2) DEFAULT '0.00',
  `status` enum('active','deleted') NOT NULL,
  `test` enum('no','yes') NOT NULL DEFAULT 'no',
  PRIMARY KEY (`id`),
  UNIQUE KEY `billing_id` (`billing_id`,`foreign_transaction_id`),
  KEY `subscription_id_type` (`subscription_id`,`type`),
  KEY `credit_id_type` (`credit_id`,`type`),
  KEY `product_type` (`product_type`,`product_id`),
  KEY `time` (`time`)
) ENGINE=InnoDB AUTO_INCREMENT=3679531 DEFAULT CHARSET=utf8;

死锁发生后，“innodb status”报告中的文本：

LATEST DETECTED DEADLOCK
------------------------
2018-12-17 12:10:38 0x2f8

***(1) TRANSACTION:

TRANSACTION 153838477815, ACTIVE 1 sec inserting
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1136, 2 row lock(s), undo log entries 1
MySQL thread id 446845346, OS thread handle 974, query id 88919281792 123.123.123.123 root update
INSERT  INTO mydb.`payments`
            SET `billing_id` = '11', `foreign_transaction_id` = '1416436', `product_type` = 'invoice', `product_id` = '232886', `type` = 'payment', `amount` = '9.99', `fee` = '0.454545', `vat` = '0', `status` = 'active', `test` = 'no'
            ON DUPLICATE KEY UPDATE `billing_id` =  '11', `foreign_transaction_id` =  '1416436', `product_type` =  'invoice', `product_id` =  '232886', `type` =  'payment', `amount` =  '9.99', `fee` =  '0.454545', `vat` =  '0', `status` =  'active', `test` =  'no', `id` = LAST_INSERT_ID(`id`)

***(1) WAITING FOR THIS LOCK TO BE GRANTED:

RECORD LOCKS space id 1898595 page no 25610 n bits 488 index billing_id of table `mydb`.`payments` trx id 153838477815 lock_mode X locks gap before rec insert intention waiting
Record lock, heap no 61 PHYSICAL RECORD: n_fields 3; compact format; info bits 0
 0: len 4; hex 0000000b; asc     ;;
 1: len 6; hex 313431363434; asc 141644;;
 2: len 4; hex 00239264; asc  # d;;

***(2) TRANSACTION:

TRANSACTION 153838477576, ACTIVE 1 sec inserting, thread declared inside InnoDB 1
mysql tables in use 1, locked 1
4 lock struct(s), heap size 1136, 3 row lock(s), undo log entries 1
MySQL thread id 446846795, OS thread handle 760, query id 88919279740 123.123.123.123 root update
INSERT  INTO mydb.`payments`
            SET `billing_id` = '11', `foreign_transaction_id` = '1416430', `product_type` = 'invoice', `product_id` = '1317214', `type` = 'payment', `amount` = '9.99', `fee` = '0.454545', `vat` = '0', `status` = 'active', `test` = 'no'
            ON DUPLICATE KEY UPDATE `billing_id` =  '11', `foreign_transaction_id` =  '1416430', `product_type` =  'invoice', `product_id` =  '1317214', `type` =  'payment', `amount` =  '9.99', `fee` =  '0.454545', `vat` =  '0', `status` =  'active', `test` =  'no', `id` = LAST_INSERT_ID(`id`)

***(2) HOLDS THE LOCK(S):

RECORD LOCKS space id 1898595 page no 25610 n bits 488 index billing_id of table `mydb`.`payments` trx id 153838477576 lock_mode X locks gap before rec
Record lock, heap no 61 PHYSICAL RECORD: n_fields 3; compact format; info bits 0
 0: len 4; hex 0000000b; asc     ;;
 1: len 6; hex 313431363434; asc 141644;;
 2: len 4; hex 00239264; asc  # d;;

***(2) WAITING FOR THIS LOCK TO BE GRANTED:

RECORD LOCKS space id 1898595 page no 25610 n bits 488 index billing_id of table `mydb`.`payments` trx id 153838477576 lock_mode X locks gap before rec insert intention waiting
Record lock, heap no 61 PHYSICAL RECORD: n_fields 3; compact format; info bits 0
 0: len 4; hex 0000000b; asc     ;;
 1: len 6; hex 313431363434; asc 141644;;
 2: len 4; hex 00239264; asc  # d;;

***WE ROLL BACK TRANSACTION (1)

我猜原因在于复合唯一索引“billing\u id”。我想知道在这种情况下mysql是如何一步一步地创建锁间隙的。又该怎么解决呢