On duplicate key update lock conditions

Access MySQL on AWS RDS

When adding API (Apache+Fuel PHP) and performing load test While Apache stopped accepting connections,
Waiting for RDS logs on RDS performance insights

synch/cond/mysys/my_thread_var::suspend

It seems that the lock has occurred.

The new MySQL code is as follows

INSERT INTO user_states
        (user_id, x, y, state)
        VALUES ('xxxxxxxx', 100, 200, 0)
        ON DUPLICATE KEY UPDATE 
        x = VALUES(x), y = VALUES(y), state = VALUES(state)

If you have a record of user_id, use the code
Create if you don't update x,y,state. This will flow asynchronously to the API for multiple user_ids containing duplicates

Table DDL has a unique index of user_id apart from PK below

CREATE TABLE `user_states`(
  `id`int(11) NOT NULL AUTO_INCREMENT,
  `user_id`varchar(255) NOT NULL,
  `x`decimal(9,6) NOT NULL,
  `y`decimal(9,6) NOT NULL,
  `state`int(11) NOT NULL DEFAULT '1',
  `created_at`datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at`datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY(`id`),
  UNIQUE KEY `index_user_states_on_user_id`(`user_id`)
ENGINE=InnoDB AUTO_INCREMENT=nnnnn DEFAULT CHARSET=latin1

I don't know if this query is the cause, but it's one of the features that I recently added. Is there a way to determine the cause of the lock on the RDS?

Also, if there is any problem with SQL or tables, please let me know

https://docs.aws.amazon.com/ja_jp/AmazonRDS/latest/AuroraUserGuide/AuroraMySQL.Reference.html

sync/cond/mysys/my_thread_var:suspend

For this wait event, the thread is stopped while waiting for the condition.For example, this event occurs when a thread is waiting for a table-level lock.It is recommended that you examine the workload to see which threads might get the table lock for the database instance.MySQL
For more information about table locking in , see Table Lock Problems in the MySQL document.