mysql deadlock

1. View transactions in progress

SELECT * FROM information_schema.INNODB_TRX;

mysql> SELECT * FROM information_schema.INNODB_TRX \G;**************************** 1. row **************************trx_id: 331123705trx_state: RUNNINGtrx_started: 2022-07-19 13:47:12trx_requested_lock_id: NULLtrx_wait_started: NULLtrx_weight: 0trx_mysql_thread_id: 11355trx_query: NULLtrx_operation_state: NULLtrx_tables_in_use: 0trx_tables_locked: 0trx_lock_structs: 0trx_lock_memory_bytes: 360trx_rows_locked: 0trx_rows_modified: 0trx_concurrency_tickets: 0trx_isolation_level: REPEATABLE READtrx_unique_checks: 1trx_foreign_key_checks: 1trx_last_foreign_key_error: NULLtrx_adaptive_hash_latched: 0trx_adaptive_hash_timeout: 10000trx_is_read_only: 0trx_autocommit_non_locking: 0**************************** 2. row **************************trx_id: 331123681trx_state: RUNNINGtrx_started: 2022-07-19 13:47:09trx_requested_lock_id: NULLtrx_wait_started: NULLtrx_weight: 397trx_mysql_thread_id: 11409trx_query: update sys_role_user ruinner join sys_role r on ru.client_role_id = r.client_role_idinner join sys_user_center uc on ru.client_user_id = uc.idset ru.role_id = r.id, ru.open_id = uc.open_idwhere (ru.role_id is null or ru.open_id is null) and ru.update_time >= '2022-07-19 13:47:09'and ru.client_id = 'webApp' and ru.`enable` = '1000102'trx_operation_state: fetching rowstrx_tables_in_use: 3trx_tables_locked: 3trx_lock_structs: 397trx_lock_memory_bytes: 63016trx_rows_locked: 109781trx_rows_modified: 0trx_concurrency_tickets: 0trx_isolation_level: REPEATABLE READtrx_unique_checks: 1trx_foreign_key_checks: 1trx_last_foreign_key_error: NULLtrx_adaptive_hash_latched: 0trx_adaptive_hash_timeout: 9974trx_is_read_only: 0trx_autocommit_non_locking: 02 rows in set (0.00 sec)

If it is found that trx_state is LOCK_WAIT, a deadlock occurs, you can use trx_mysql_thread_id mysql thread, and pass kill thread kill thread

2 . View locked transactions

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCKS;

3. View transactions waiting for locks

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS;

4. Check whether the table is locked

SHOW OPEN TABLES where In_use > 0;

5. Resolving deadlocks

Remove deadlock

If you need to remove the deadlock, there is one of the simplest and rude ways, that is, after finding the process id, kill it directly.

View currently ongoing processes

show processlist

// Also available

SELECT * FROM information_schema.INNODB_TRX;

The process id found by these two commands is the same.

kill the process corresponding to the process

kill id

Verify (after killing to see if there is still a lock)

SHOW OPEN TABLES where In_use > 0;