Lock Monitoring Scripts

>>Script Language and Platform: SQL / MySQL
This sequence of scripts can help identify tables that are being blocked and quantify how many locks are happening in your database.

Author: Carlos Victor

	-- Who is blocking (BLOCKING_TRX_ID | BLOCKING_LOCK_ID)

SELECT  TRX.TRX_MYSQL_THREAD_ID,
 TRX.TRX_ISOLATION_LEVEL,
 TRX.TRX_STARTED,
 TRX.TRX_STATE,
 PROCESSLIST.USER,
 PROCESSLIST.HOST,
 PROCESSLIST.DB,
 PROCESSLIST.COMMAND,
 PROCESSLIST.TIME,
 PROCESSLIST.STATE,
 LOCK_WAITS.REQUESTING_TRX_ID,
 LOCK_WAITS.BLOCKING_TRX_ID,
 LOCK_WAITS.BLOCKING_LOCK_ID
FROM INFORMATION_SCHEMA.INNODB_LOCKS LOCKS,
     INFORMATION_SCHEMA.INNODB_TRX TRX,
     INFORMATION_SCHEMA.PROCESSLIST PROCESSLIST,
     INFORMATION_SCHEMA.INNODB_LOCK_WAITS LOCK_WAITS WHERE LOCKS.LOCK_TRX_ID = TRX.TRX_ID
  AND TRX.TRX_MYSQL_THREAD_ID = PROCESSLIST.ID;

-- Query #2

SELECT r.trx_id waiting_trx_id, r.trx_mysql_thread_id waiting_thread, r.trx_query waiting_query, b.trx_id blocking_trx_id, b.trx_mysql_thread_id blocking_thread, b.trx_query blocking_query, bl.lock_id blocking_lock_id, bl.lock_mode blocking_lock_mode, bl.lock_type blocking_lock_type, bl.lock_table blocking_lock_table, bl.lock_index blocking_lock_index, rl.lock_id waiting_lock_id, rl.lock_mode waiting_lock_mode, rl.lock_type waiting_lock_type, rl.lock_table waiting_lock_table, rl.lock_index waiting_lock_index FROM information_schema.INNODB_LOCK_WAITS w INNER JOIN information_schema.INNODB_TRX b ON b.trx_id = w.blocking_trx_id INNER JOIN information_schema.INNODB_TRX r ON r.trx_id = w.requesting_trx_id INNER JOIN information_schema.INNODB_LOCKS bl ON bl.lock_id = w.blocking_lock_id INNER JOIN information_schema.INNODB_LOCKS rl ON rl.lock_id = w.requested_lock_id; 

-- Query #3

SELECT blocking_trx_id,COUNT(*), b.trx_query blocking_query, MIN(r.trx_wait_started) FROM information_schema.INNODB_LOCK_WAITS w INNER JOIN information_schema.INNODB_TRX b ON b.trx_id = w.blocking_trx_id INNER JOIN information_schema.INNODB_TRX r ON r.trx_id = w.requesting_trx_id INNER JOIN information_schema.INNODB_LOCKS bl ON bl.lock_id = w.blocking_lock_id INNER JOIN information_schema.INNODB_LOCKS rl ON rl.lock_id = w.requested_lock_id GROUP BY blocking_trx_id ORDER BY COUNT(*) DESC;


-- A list of blocking transactions

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCKS WHERE LOCK_TRX_ID IN (SELECT BLOCKING_TRX_ID FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS);

OR

SELECT INNODB_LOCKS.*
FROM INFORMATION_SCHEMA.INNODB_LOCKS
JOIN INFORMATION_SCHEMA.INNODB_LOCK_WAITS
  ON (INNODB_LOCKS.LOCK_TRX_ID = INNODB_LOCK_WAITS.BLOCKING_TRX_ID);

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