Lock wait timeout exceeded solution

[Err] 1205 - Lock wait timeout exceeded; try restarting transaction

Basic reason: The post-committed transaction waits for the previously processed transaction to release the lock, but when waiting exceeds the lock waiting time of mysql, this exception will be raised.

1. Find the locked statement by going to information_schema

information_schemaThis data table saves the information of all databases on the MySQL server.Such as database name, database table, table column data type and access rights.To put it simply, on this MySQL server, which databases are there, which tables are in each database, what are the field types of each table, what permissions are required for each database to access, and so on, the information is stored in the information_schema table.

mysql version before 8: information_schema

• innodb_trxall currently running transactions
• innodb_lockscurrently present locks
• innodb_lock_waitscorrespondence of lock waiting

select * from information_schema.innodb_trx;
select * from information_schema.innodb_locks;
select * from information_schema.innodb_locks_waits;

mysql version after 8.0: performance_schema

• innodb_trxall currently running transactions
• innodb_lockscurrently present locks
• innodb_lock_waitscorrespondence of lock waiting

select * from information_schema.innodb_trx;
select * from performance_schema.data_locks;
select * from performance_schema.data_lock_waits;

2. There is a lock in the query database

select * from information_schema.innodb_trx;

The record status is "RUNNING", that is, the transaction is being executed, and there is no lock

3. Show running threads

show full processlist;

Then find out the system id of the query statement: kill the locked thread id

kill 5