• MySQL 锁的监控及处理


    故障模拟

    # 添加两项配置
    vi /etc/my.cnf
    [mysqld]
    autocommit=0
    innodb_lock_wait_timeout = 3600
    
    systemctl restart mysqld
    
    # 登录数据库
    use klvchen;
    UPDATE t1 SET k1='av' WHERE id=1;
    
    # 新开一个窗口,再登录数据库
    use klvchen;
    UPDATE t1 SET k1='az' WHERE id=1;
    # 此时页面卡住
    

    (一)看有没有锁等待

    # 新开一个窗口,登录数据库
    SHOW  STATUS LIKE 'innodb_row_lock%';
    +-------------------------------+-------+
    | Variable_name                 | Value |
    +-------------------------------+-------+
    | Innodb_row_lock_current_waits | 1     |        # 当前正在等待锁的数量;
    | Innodb_row_lock_time          | 0     |        # 从系统启动到现在锁定总时间长度;
    | Innodb_row_lock_time_avg      | 0     |        # 每次等待所花平均时间;
    | Innodb_row_lock_time_max      | 0     |        # 从系统启动到现在等待最长的一次所花的时间长度;
    | Innodb_row_lock_waits         | 1     |        # 系统启动到现在总共等待的次数;
    +-------------------------------+-------+
    

    (二)查看哪个事务在等待(被阻塞了)

    USE information_schema;
    SELECT * FROM information_schema.INNODB_TRX WHERE trx_state='LOCK WAIT'G;
    *************************** 1. row ***************************
                        trx_id: 14597                               # 事务ID号
                     trx_state: LOCK WAIT                           # 当前事务的状态
                   trx_started: 2019-12-21 09:20:25
         trx_requested_lock_id: 14597:32:3:2
              trx_wait_started: 2019-12-21 09:20:25
                    trx_weight: 2
           trx_mysql_thread_id: 3                                   # 连接层的,连接线程ID(SHOW PROCESSLIST ===>Id或trx_id )
                     trx_query: UPDATE t1 SET k1='az' WHERE id=1    # 当前被阻塞的操作(一般是要丢给开发的)
           trx_operation_state: starting index read
             trx_tables_in_use: 1
             trx_tables_locked: 1
              trx_lock_structs: 2
         trx_lock_memory_bytes: 1136
               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: 0
              trx_is_read_only: 0
    trx_autocommit_non_locking: 0
    
    # 或者你可以简单地进行查看
    select trx_state,trx_started,trx_wait_started,trx_weight,trx_rows_locked,now() from information_schema.innodb_trx;
    
    # 字段说明:
    trx_state            事务状态,有以下几种状态:RUNNING、LOCK WAIT、ROLLING BACK 和 COMMITTING
    trx_started          事务开始时间
    trx_wait_started     事务开始等待的时间
    trx_weight           事务的权重
    trx_rows_locked      事务锁住的记录数,包含标记为 DELETED,并且已经保存到磁盘但对事务不可见的行
    

    (三)查看锁源,谁锁的我

    SELECT * FROM sys.innodb_lock_waitsG;                          # 被锁的和锁定它的之间关系
    *************************** 1. row ***************************
                    wait_started: 2019-12-21 09:20:25
                        wait_age: 00:01:30
                   wait_age_secs: 90
                    locked_table: `klvchen`.`t1`                    # 哪张表出现的等待 
                    locked_index: GEN_CLUST_INDEX
                     locked_type: RECORD
                  waiting_trx_id: 14597                             # 等待的事务(与上个视图trx_id 对应)
             waiting_trx_started: 2019-12-21 09:20:25
                 waiting_trx_age: 00:01:30
         waiting_trx_rows_locked: 1
       waiting_trx_rows_modified: 0
                     waiting_pid: 3                                 # 等待的线程号(与上个视图trx_mysql_thread_id)
                   waiting_query: UPDATE t1 SET k1='az' WHERE id=1
                 waiting_lock_id: 14597:32:3:2
               waiting_lock_mode: X
                 blocking_trx_id: 14596                             # 锁源的事务ID 
                    blocking_pid: 2                                 # 锁源的线程号
                  blocking_query: NULL
                blocking_lock_id: 14596:32:3:2
              blocking_lock_mode: X
            blocking_trx_started: 2019-12-21 09:20:12
                blocking_trx_age: 00:01:43
        blocking_trx_rows_locked: 5
      blocking_trx_rows_modified: 0
         sql_kill_blocking_query: KILL QUERY 2
    sql_kill_blocking_connection: KILL 2
    

    (四)找到锁源的 thread_id

    SELECT * FROM performance_schema.threads WHERE processlist_id=2G;
    *************************** 1. row ***************************
              THREAD_ID: 27
                   NAME: thread/sql/one_connection
                   TYPE: FOREGROUND
         PROCESSLIST_ID: 2
       PROCESSLIST_USER: root
       PROCESSLIST_HOST: localhost
         PROCESSLIST_DB: klvchen
    PROCESSLIST_COMMAND: Sleep
       PROCESSLIST_TIME: 261
      PROCESSLIST_STATE: NULL
       PROCESSLIST_INFO: UPDATE t1 SET k1='av' WHERE id=1
       PARENT_THREAD_ID: 1
                   ROLE: NULL
           INSTRUMENTED: YES
                HISTORY: YES
        CONNECTION_TYPE: Socket
           THREAD_OS_ID: 2557
    

    (五)找到锁源的SQL语句

    -- 当前在执行的语句
    SELECT * FROM performance_schema.`events_statements_current` WHERE thread_id=27G;
    *************************** 1. row ***************************
                  THREAD_ID: 27
                   EVENT_ID: 8
               END_EVENT_ID: 8
                 EVENT_NAME: statement/sql/update
                     SOURCE: 
                TIMER_START: 16785505578000
                  TIMER_END: 16785741560000
                 TIMER_WAIT: 235982000
                  LOCK_TIME: 126000000
                   SQL_TEXT: UPDATE t1 SET k1='av' WHERE id=1
                     DIGEST: c75120019b1993cf2423bd9add827987
                DIGEST_TEXT: UPDATE `t1` SET `k1` = ? WHERE `id` = ? 
             CURRENT_SCHEMA: klvchen
                OBJECT_TYPE: NULL
              OBJECT_SCHEMA: NULL
                OBJECT_NAME: NULL
      OBJECT_INSTANCE_BEGIN: NULL
                MYSQL_ERRNO: 0
          RETURNED_SQLSTATE: 00000
               MESSAGE_TEXT: Rows matched: 1  Changed: 0  Warnings: 0
                     ERRORS: 0
                   WARNINGS: 0
              ROWS_AFFECTED: 0
                  ROWS_SENT: 0
              ROWS_EXAMINED: 4
    CREATED_TMP_DISK_TABLES: 0
         CREATED_TMP_TABLES: 0
           SELECT_FULL_JOIN: 0
     SELECT_FULL_RANGE_JOIN: 0
               SELECT_RANGE: 0
         SELECT_RANGE_CHECK: 0
                SELECT_SCAN: 0
          SORT_MERGE_PASSES: 0
                 SORT_RANGE: 0
                  SORT_ROWS: 0
                  SORT_SCAN: 0
              NO_INDEX_USED: 0
         NO_GOOD_INDEX_USED: 0
           NESTING_EVENT_ID: NULL
         NESTING_EVENT_TYPE: NULL
        NESTING_EVENT_LEVEL: 0
    
    -- 执行语句的历史
    SELECT * FROM performance_schema.`events_statements_history` WHERE thread_id=27G;
    

    得出结果,丢给开发
    表信息
    被阻塞的
    锁源SQL

    快速方法

    方法 一

    # 查看有没有锁表
    SHOW  STATUS LIKE 'innodb_row_lock%';
    
    # 获取正在等待的语句,kill 锁源语句,锁源ID,锁源线程ID
    select a.waiting_query  as '被锁住的SQL语句', a.sql_kill_blocking_connection, a.blocking_pid, b.THREAD_ID AS '锁源线程ID'
    from
    (SELECT waiting_query, sql_kill_blocking_connection, blocking_pid FROM sys.innodb_lock_waits) a, 
    (SELECT THREAD_ID, PROCESSLIST_ID FROM performance_schema.threads WHERE processlist_id IN (SELECT blocking_pid FROM sys.innodb_lock_waits)) b 
    where a.blocking_pid = b.PROCESSLIST_ID order by b.THREAD_ID;
    
    # 查出锁源 SQL 语句
    SELECT THREAD_ID, SQL_TEXT AS '锁源当前执行的SQL语句' ,CURRENT_SCHEMA AS '数据库' FROM performance_schema.`events_statements_current` WHERE thread_id IN (SELECT THREAD_ID FROM performance_schema.threads pt WHERE processlist_id IN (SELECT blocking_pid FROM sys.innodb_lock_waits));
    

    方法 二

    # 查看有没有锁表
    SHOW  STATUS LIKE 'innodb_row_lock%';
    
    # 获取正在等待的语句,kill 锁源语句,锁源ID
    SELECT waiting_query as '被锁住的SQL语句',sql_kill_blocking_connection,blocking_pid FROM sys.innodb_lock_waits;
    
    # 查找对应关系
    SELECT THREAD_ID AS '锁源线程ID', PROCESSLIST_ID FROM performance_schema.threads WHERE processlist_id IN (SELECT blocking_pid FROM sys.innodb_lock_waits);
    
    # 查出锁源 SQL 语句
    SELECT THREAD_ID, SQL_TEXT AS '锁源当前执行的SQL语句' ,CURRENT_SCHEMA AS '数据库' FROM performance_schema.`events_statements_current` WHERE thread_id IN (SELECT THREAD_ID FROM performance_schema.threads pt WHERE processlist_id IN (SELECT blocking_pid FROM sys.innodb_lock_waits));
    
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  • 原文地址:https://www.cnblogs.com/klvchen/p/12076019.html
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