The normal method of MySQL deadlock check processing

#step 1: Window 1mysql> start transaction;
mysql> update aa set name='aaa' where id = 1;
 
#step 2: Window 2mysql> start transaction;
mysql> update bb set name='bbb' where id = 1;
 
#step 3: Window 1mysql> update bb set name='bbb';

#step 4: Window 3#Whether to submit automaticallymysql> show variables like 'autocommit';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| autocommit | ON |
+---------------+-------+
 
#View the current connectionmysql> show processlist;
mysql> show full processlist;
mysql> SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST;
+----+------+-----------+------+---------+------+-------+-----------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+------+---------+------+-------+-----------------+
| 4 | root | localhost | test | Sleep | 244 | | NULL |
| 5 | root | localhost | test | Sleep | 111 | | NULL |
| 6 | root | localhost | NULL | Query | 0 | init | show processlist |
+----+------+-----------+------+---------+------+-------+-----------------+
 
 
#View the currently locked transaction (cannot be found after the lock request times out)
mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCKS;
+------------------+-------------+-----------+-----------+-------------+-----------------+------------+-----------+----------+----------------+
| lock_id | lock_trx_id | lock_mode | lock_type | lock_table | lock_index | lock_space | lock_page | lock_rec | lock_data |
+------------------+-------------+-----------+-----------+-------------+-----------------+------------+-----------+----------+----------------+
| 130718495:65:3:4 | 130718495 | X | RECORD | `test`.`bb` | GEN_CLUST_INDEX | 65 | 3 | 4 | 0x000000000300 |
| 130718496:65:3:4 | 130718496 | X | RECORD | `test`.`bb` | GEN_CLUST_INDEX | 65 | 3 | 4 | 0x000000000300 |
+------------------+-------------+-----------+-----------+-------------+-----------------+------------+-----------+----------+----------------+
 
#View the transactions currently waiting for locks (cannot be found after the lock request times out)
mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS; 
+-------------------+-------------------+-----------------+------------------+
| requesting_trx_id | requested_lock_id | blocking_trx_id | blocking_lock_id |
+-------------------+-------------------+-----------------+------------------+
| 130718499 | 130718499:65:3:4 | 130718500 | 130718500:65:3:4 |
+-------------------+-------------------+-----------------+------------------+
 
 
#View the current uncommitted transaction (if the deadlock wait times out, the transaction may not be closed yet)
mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_TRX;
+--------------------------------------------------------------------------------------------------------+
| trx_id | trx_state | trx_started | trx_requested_lock_id | trx_wait_started | trx_weight |
+-----------+-----------+---------------------+-----------------------+---------------------+------------+
| 130718500 | RUNNING | 2018-03-12 09:28:10 | NULL | NULL | 3 |
| 130718499 | LOCK WAIT | 2018-03-12 09:27:59 | 130718499:65:3:4 | 2018-03-12 09:32:48 | 5 |
==========================================================================================================
| trx_mysql_thread_id | trx_query | trx_operation_state | trx_tables_in_use |
+---------------------+---------------------------------------+---------------------+-------------------+
| 4 | NULL | NULL | 0 |
| 5 | update bb set name='bbb' | starting index read | 1 |
=========================================================================================================
| trx_tables_locked | trx_lock_structs | trx_lock_memory_bytes | trx_rows_locked | trx_rows_modified |
+-------------------+------------------+-----------------------+-------------------+-------------------+
| 0 | 2 | 360 | 3 | 1 |
| 1 | 4 | 1184 | 4 | 1 |
===========================================================================================================================
| trx_concurrency_tickets | trx_isolation_level | trx_unique_checks | trx_foreign_key_checks | trx_last_foreign_key_error |
+-------------------------+---------------------+-------------------+------------------------+----------------------------+
| 0 | REPEATABLE READ | 1 | 1 | NULL |
| 0 | REPEATABLE READ | 1 | 1 | NULL |
===========================================================================================================================
| trx_adaptive_hash_latched | trx_adaptive_hash_timeout | trx_is_read_only | trx_autocommit_non_locking |
+---------------------------+---------------------------+------------------+----------------------------+
| 0 | 10000 | 0 | 0 |
| 0 | 10000 | 0 | 0 |
+---------------------------+---------------------------+------------------+----------------------------+
 
 
#View the tables being accessed mysql> show OPEN TABLES where In_use > 0;
+----------+-------+--------+-------------+
| Database | Table | In_use | Name_locked |
+----------+-------+--------+-------------+
| test | bb | 1 | 0 |
+----------+-------+--------+-------------+

#step 3: Window 1 (If the lock request in step 3 takes too long, the lock will time out and the execution will be terminated)
mysql> update bb set name='bbb';
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
 
 
#Before the lock request of "window one" times out, execute step 5 to cause a deadlock. Then the execution of the connection "window two" is terminated, and "window one" is successfully executed. #step 5: Window twomysql> update aa set name='aa';
ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction

#View the most recent deadlock situationmysql> SHOW ENGINE INNODB STATUS\G;
...............
------------------------
LATEST DETECTED DEADLOCK
------------------------
2018-03-12 11:01:06 7ffb4993a700 #Occurrence time*** (1) TRANSACTION: #Transaction 1
TRANSACTION 130718515, ACTIVE 19 sec starting index read
mysql tables in use 1, locked 1 #table being accessed LOCK WAIT 4 lock struct(s), heap size 1184, 4 row lock(s), undo log entries 1 #number of rows affected MySQL thread id 5, OS thread handle 0x7ffb498f8700, query id 205 localhost root updating #thread/connection host/userupdate bb set name='bb' #request statement*** (1) WAITING FOR THIS LOCK TO BE GRANTED: #waiting for the following resources (lock position and lock mode)
RECORD LOCKS space id 65 page no 3 n bits 72 index `GEN_CLUST_INDEX` of table `test`.`bb` trx id 130718515 lock_mode X waiting
Record lock, heap no 5 PHYSICAL RECORD: n_fields 5; compact format; info bits 0
 0: len 6; hex 000000000300; asc ;;
 1: len 6; hex 000007ca9b34; asc 4;;
 2: len 7; hex 1f000002092075; asc u;;
 3: len 4; hex 80000001; asc ;;
 4: len 2; hex 6262; asc bb;;
 
*** (2) TRANSACTION: #Transaction 2
TRANSACTION 130718516, ACTIVE 14 sec starting index read
mysql tables in use 1, locked 1
4 lock struct(s), heap size 1184, 4 row lock(s), undo log entries 1
MySQL thread id 4, OS thread handle 0x7ffb4993a700, query id 206 localhost root updating
update aa set name='aa' #Request statement*** (2) HOLDS THE LOCK(S): #Holding lock resources RECORD LOCKS space id 65 page no 3 n bits 72 index `GEN_CLUST_INDEX` of table `test`.`bb` trx id 130718516 lock_mode X
Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0
 0: len 8; hex 73757072656d756d; asc supremum;;
 
Record lock, heap no 3 PHYSICAL RECORD: n_fields 5; compact format; info bits 0
 0: len 6; hex 000000000301; asc ;;
 1: len 6; hex 000007ca9b17; asc ;;
 2: len 7; hex 9000000144011e; asc D ;;
 3: len 4; hex 80000002; asc ;;
 4: len 2; hex 6262; asc bb;;
 
Record lock, heap no 5 PHYSICAL RECORD: n_fields 5; compact format; info bits 0
 0: len 6; hex 000000000300; asc ;;
 1: len 6; hex 000007ca9b34; asc 4;;
 2: len 7; hex 1f000002092075; asc u;;
 3: len 4; hex 80000001; asc ;;
 4: len 2; hex 6262; asc bb;;
 
*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 64 page no 3 n bits 80 index `GEN_CLUST_INDEX` of table `test`.`aa` trx id 130718516 lock_mode X waiting
Record lock, heap no 7 PHYSICAL RECORD: n_fields 5; compact format; info bits 0
 0: len 6; hex 000000000200; asc ;;
 1: len 6; hex 000007ca9b33; asc 3;;
 2: len 7; hex 1e000001d53057; asc 0W;;
 3: len 4; hex 80000001; asc ;;
 4: len 2; hex 6161; asc aa;;
 
*** WE ROLL BACK TRANSACTION (2)
...............

#Deadlock records only record the most recent deadlock information. To save each deadlock information to the error log, enable the following parameters:
mysql> show variables like 'innodb_print_all_deadlocks';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| innodb_print_all_deadlocks | OFF |
+----------------------------+-------+
 
 
#If the resource cannot be requested in [step 3: window 1] above, the lock wait timeout will occur after the default of 50 seconds.
mysql> show variables like 'innodb_lock_wait_timeout'; 
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| innodb_lock_wait_timeout | 50 |
+--------------------------+-------+
 
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
 
 
#Set the global variable lock waiting timeout to 60 seconds (new connection takes effect)
#mysql> set session innodb_lock_wait_timeout=50; 
mysql> set global innodb_lock_wait_timeout=60; 
 
 
#In the above test, when a statement in a transaction times out, only the statement is rolled back, and the integrity of the transaction is destroyed. To rollback this transaction, enable the following parameters:
mysql> show variables like 'innodb_rollback_on_timeout';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| innodb_rollback_on_timeout | OFF |
+----------------------------+-------+

[mysqld]
log-error=/var/log/mysqld3306.log
innodb_lock_wait_timeout=60 #Lock request timeout (seconds)
innodb_rollback_on_timeout = 1 #If a lock request of a statement in a transaction times out, the entire transaction will be rolled back innodb_print_all_deadlocks = 1 #All deadlocks are saved to the error log

#If you delete the blocked session manually, delete the one with Command='Sleep', no State, no Info, and the smallest trx_weight.
show processlist;
SELECT trx_mysql_thread_id,trx_state,trx_started,trx_weight FROM INFORMATION_SCHEMA.INNODB_TRX;