MySQL innodb_lock_wait 鎖等待

SELECT * FROM innodb_trx; SELECT * FROM innodb_lock_waits; SELECT * FROM innodb_locks;

MySQL 5.5 -- innodb_lock_wait 鎖 等待 記得之前，當出現：ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction， 要解決是一件麻煩的事情 ； 特別是當一個SQL執行完了，但未COMMIT，後面的SQL想要執行就是被鎖，超時結束； DBA光從數據庫沒法着手找出源頭是哪一個SQL鎖住了； 有時候看看show engine innodb status , 並結合 show full processlist; 能暫時解決問題；但一直不能精肯定位； 在5.5中，information_schema 庫中增長了三個關於鎖的表（MEMORY引擎）； innodb_trx ## 當前運行的全部事務 innodb_locks ## 當前出現的鎖 innodb_lock_waits ## 鎖等待的對應關係 看到這個就很是激動 ； 這但是解決了一個大麻煩，先來看一下表結構

root@127.0.0.1 : information_schema 13:28:38> desc innodb_locks; +-------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------------+------+-----+---------+-------+ | lock_id | varchar(81) | NO | | | |#鎖ID | lock_trx_id | varchar(18) | NO | | | |#擁有鎖的事務ID | lock_mode | varchar(32) | NO | | | |#鎖模式 | lock_type | varchar(32) | NO | | | |#鎖類型 | lock_table | varchar(1024) | NO | | | |#被鎖的表 | lock_index | varchar(1024) | YES | | NULL | |#被鎖的索引 | lock_space | bigint(21) unsigned | YES | | NULL | |#被鎖的表空間號 | lock_page | bigint(21) unsigned | YES | | NULL | |#被鎖的頁號 | lock_rec | bigint(21) unsigned | YES | | NULL | |#被鎖的記錄號 | lock_data | varchar(8192) | YES | | NULL | |#被鎖的數據 +-------------+---------------------+------+-----+---------+-------+ 10 rows in set (0.00 sec)

root@127.0.0.1 : information_schema 13:28:56> desc innodb_lock_waits; +-------------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+-------------+------+-----+---------+-------+ | requesting_trx_id | varchar(18) | NO | | | |#請求鎖的事務ID | requested_lock_id | varchar(81) | NO | | | |#請求鎖的鎖ID | blocking_trx_id | varchar(18) | NO | | | |#當前擁有鎖的事務ID | blocking_lock_id | varchar(81) | NO | | | |#當前擁有鎖的鎖ID +-------------------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)

root@127.0.0.1 : information_schema 13:29:05> desc innodb_trx ; +----------------------------+---------------------+------+-----+---------------------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------------------+---------------------+------+-----+---------------------+-------+ | trx_id | varchar(18) | NO | | | |#事務ID | trx_state | varchar(13) | NO | | | |#事務狀態： | trx_started | datetime | NO | | 0000-00-00 00:00:00 | |#事務開始時間； | trx_requested_lock_id | varchar(81) | YES | | NULL | |#innodb_locks.lock_id | trx_wait_started | datetime | YES | | NULL | |#事務開始等待的時間 | trx_weight | bigint(21) unsigned | NO | | 0 | |# | trx_mysql_thread_id | bigint(21) unsigned | NO | | 0 | |#事務線程ID | trx_query | varchar(1024) | YES | | NULL | |#具體SQL語句 | trx_operation_state | varchar(64) | YES | | NULL | |#事務當前操做狀態 | trx_tables_in_use | bigint(21) unsigned | NO | | 0 | |#事務中有多少個表被使用 | trx_tables_locked | bigint(21) unsigned | NO | | 0 | |#事務擁有多少個鎖 | trx_lock_structs | bigint(21) unsigned | NO | | 0 | |# | trx_lock_memory_bytes | bigint(21) unsigned | NO | | 0 | |#事務鎖住的內存大小（B） | trx_rows_locked | bigint(21) unsigned | NO | | 0 | |#事務鎖住的行數 | trx_rows_modified | bigint(21) unsigned | NO | | 0 | |#事務更改的行數 | trx_concurrency_tickets | bigint(21) unsigned | NO | | 0 | |#事務併發票數 | trx_isolation_level | varchar(16) | NO | | | |#事務隔離級別 | trx_unique_checks | int(1) | NO | | 0 | |#是否惟一性檢查 | trx_foreign_key_checks | int(1) | NO | | 0 | |#是否外鍵檢查 | trx_last_foreign_key_error | varchar(256) | YES | | NULL | |#最後的外鍵錯誤 | trx_adaptive_hash_latched | int(1) | NO | | 0 | |# | trx_adaptive_hash_timeout | bigint(21) unsigned | NO | | 0 | |# +----------------------------+---------------------+------+-----+---------------------+-------+ 22 rows in set (0.01 sec) 下面咱們來動手看看數據吧： ##創建測試數據： use test; create table tx1 (id int primary key , c1 varchar(20), c2 varchar(30)) engine=innodb default charset = utf8 ; insert into tx1 values (1,'aaaa','aaaaa2'), (2,'bbbb','bbbbb2'), (3,'cccc','ccccc2'); commit; ###產生事務；

Session1

start transaction; update tx1 set c1='heyf',c2='heyf' where id =3 ;

產生事務，在innodb_trx就有數據 ；

root@127.0.0.1 : information_schema 13:38:21> select * from innodb_trx G *************************** 1. row *************************** trx_id: 3669D82 trx_state: RUNNING trx_started: 2010-12-24 13:38:06 trx_requested_lock_id: NULL trx_wait_started: NULL trx_weight: 3 trx_mysql_thread_id: 2344 trx_query: NULL trx_operation_state: NULL trx_tables_in_use: 0 trx_tables_locked: 0 trx_lock_structs: 2 trx_lock_memory_bytes: 376 trx_rows_locked: 1 trx_rows_modified: 1 trx_concurrency_tickets: 0 trx_isolation_level: REPEATABLE READ trx_unique_checks: 1 trx_foreign_key_checks: 1 trx_last_foreign_key_error: NULL trx_adaptive_hash_latched: 0 trx_adaptive_hash_timeout: 10000 1 row in set (0.00 sec)

因爲沒有產生鎖等待，下面兩個表沒有數據 ；

root@127.0.0.1 : information_schema 13:38:31> select * from innodb_lock_waits G Empty set (0.00 sec) root@127.0.0.1 : information_schema 13:38:57> select * from innodb_locks G Empty set (0.00 sec)

產生鎖等待

session 2

start transaction; update tx1 set c1='heyfffff',c2='heyffffff' where id =3 ;

root@127.0.0.1 : information_schema 13:39:01> select * from innodb_trx G *************************** 1. row *************************** trx_id: 3669D83 ##第2個事務 trx_state: LOCK WAIT ## 處於等待狀態 trx_started: 2010-12-24 13:40:07 trx_requested_lock_id: 3669D83:49:3:4 ##請求的鎖ID trx_wait_started: 2010-12-24 13:40:07 trx_weight: 2 trx_mysql_thread_id: 2346 ##線程 ID trx_query: update tx1 set c1='heyfffff',c2='heyffffff' where id =3 trx_operation_state: starting index read trx_tables_in_use: 1 ##須要用到1個表 trx_tables_locked: 1 ##有1個表被鎖 trx_lock_structs: 2 trx_lock_memory_bytes: 376 trx_rows_locked: 1 trx_rows_modified: 0 trx_concurrency_tickets: 0 trx_isolation_level: REPEATABLE READ trx_unique_checks: 1 trx_foreign_key_checks: 1 trx_last_foreign_key_error: NULL trx_adaptive_hash_latched: 0 trx_adaptive_hash_timeout: 10000 *************************** 2. row *************************** trx_id: 3669D82 ##第1個事務 trx_state: RUNNING trx_started: 2010-12-24 13:38:06 trx_requested_lock_id: NULL trx_wait_started: NULL trx_weight: 3 trx_mysql_thread_id: 2344 trx_query: NULL trx_operation_state: NULL trx_tables_in_use: 0 trx_tables_locked: 0 trx_lock_structs: 2 trx_lock_memory_bytes: 376 trx_rows_locked: 1 trx_rows_modified: 1 trx_concurrency_tickets: 0 trx_isolation_level: REPEATABLE READ trx_unique_checks: 1 trx_foreign_key_checks: 1 trx_last_foreign_key_error: NULL trx_adaptive_hash_latched: 0 trx_adaptive_hash_timeout: 10000 2 rows in set (0.00 sec) root@127.0.0.1 : information_schema 13:40:12> select * from innodb_locks G *************************** 1. row *************************** lock_id: 3669D83:49:3:4 ## 第2個事務須要的鎖 lock_trx_id: 3669D83 lock_mode: X lock_type: RECORD lock_table: test.tx1 lock_index: PRIMARY lock_space: 49 lock_page: 3 lock_rec: 4 lock_data: 3 *************************** 2. row *************************** lock_id: 3669D82:49:3:4 ## 第1個事務須要的鎖 lock_trx_id: 3669D82 lock_mode: X lock_type: RECORD lock_table: test.tx1 lock_index: PRIMARY lock_space: 49 lock_page: 3 lock_rec: 4 lock_data: 3 2 rows in set (0.00 sec) root@127.0.0.1 : information_schema 13:40:15> select * from innodb_lock_waits G *************************** 1. row *************************** requesting_trx_id: 3669D83 ## 請求鎖的事務 requested_lock_id: 3669D83:49:3:4 ## 請求鎖的鎖ID blocking_trx_id: 3669D82 ## 擁有鎖的事務 blocking_lock_id: 3669D82:49:3:4 ## 擁有鎖的鎖ID 1 row in set (0.00 sec)

哈哈，有了以上這些信息，如下問題就迎刃而解啦。 當前有哪些事務在等待鎖？ 這些鎖須要鎖哪些表，鎖哪些索引，鎖哪些記錄和值 ？ 處於等待狀態的相關SQL是什麼？ 在等待哪些事務完成 ？ 擁有當前鎖的SQL是什麼？ 我想這些SQL對DBA來講不難吧？ 你們本身動手吧。