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【FAQ系列】复制线程长时间Opening tablesnew

前言:在slave上,发现SQL thread长时间处于Opening tables状态

1、问题描述

朋友的数据库,做了主从replication复制。在slave实例上,SQL thread的长时间处于Opening tables状态,复制进程异常。

【FAQ系列】复制线程长时间Opening tablesnew

整个实例大概20个database,总共300G左右。

master是5.5版本,slave是5.6版本,master上执行xtrabackup全库备份后搭建的slave。

2、原因分析

我的第一反应是table cache是不是太小了,导致open table比较慢,所以才长时间处于这个状态。无论如何,先一层层排查吧。

先看下slave status(部分无用信息我隐掉了):

mysql> show slave status/G

*************************** 1. row ***************************

Slave_IO_State: Queueing master event to the relay log

Master_Log_File: master-bin.000618

Read_Master_Log_Pos: 614915856

Relay_Log_File: replicate.000008

Relay_Log_Pos: 2384117

Relay_Master_Log_File: master-bin.000617

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

Replicate_Do_DB:

Replicate_Ignore_DB:

Replicate_Do_Table:

Replicate_Ignore_Table:

Replicate_Wild_Do_Table:

Replicate_Wild_Ignore_Table:

Last_Errno: 0

Last_Error:

Skip_Counter: 0

Exec_Master_Log_Pos: 252048331

Relay_Log_Space: 1438994074

Until_Condition: None

Until_Log_File:

Until_Log_Pos: 0

Seconds_Behind_Master: 59240

Master_SSL_Verify_Server_Cert: No

Last_IO_Errno: 0

Last_IO_Error:

Last_SQL_Errno: 0

Last_SQL_Error:

Replicate_Ignore_Server_Ids:

Master_Server_Id: 1

Master_UUID:

Master_Info_File: /home/mysql/master.info

SQL_Delay: 0

SQL_Remaining_Delay: NULL

Slave_SQL_Running_State: Opening tables

Master_Retry_Count: 86400

Last_IO_Error_Timestamp:

Last_SQL_Error_Timestamp:

Master_SSL_Crlpath:

Retrieved_Gtid_Set:

Executed_Gtid_Set:

Auto_Position: 0

看不出来有什么异常的。

再看下系统负载情况:

[root@localhost mysql]# vmstat -S m 1

procs ———–memory———- —swap– —–io—- –system– —–cpu—–

r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st

0  2      1  19591    458 230576    0    0    11    20    0    0  0  0 100  0  0

1  1      1  19587    458 230579    0    0  2032  2528 1645  584  1  1 93  4  0

1  1      1  19583    458 230582    0    0  1664  2712 1773  461  1  1 93  4  0

0  2      1  19578    458 230585    0    0  2080  3376 1810  660  1  1 93  4  0

2  0      1  19576    458 230587    0    0  2224  1804 1634  594  1  1 94  4  0

3  1      1  19569    458 230590    0    0  1968  3488 1693  566  1  1 93  4  0

1  1      1  19567    458 230593    0    0  2016  2632 1775  515  1  1 93  4  0

[root@localhost mysql]# sar -d 1

Linux 2.6.32-431.el6.x86_64 (localhost.localdomain)     03/21/2015      _x86_64_        (24 CPU)

03:21:57 PM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util

03:21:58 PM    dev8-0    185.86   5753.54     64.65     31.30      1.20      6.48      5.08     94.44

03:21:58 PM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util

03:21:59 PM    dev8-0    197.03   6114.85     95.05     31.52      1.16      5.88      4.48     88.32

03:21:59 PM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util

03:22:00 PM    dev8-0    188.89   5882.83     88.89     31.61      1.14      6.03      5.09     96.16

03:22:00 PM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util

03:22:01 PM    dev8-0    166.00   5152.00     80.00     31.52      1.42      8.56      5.58     92.70

也看不出来异常,继续看看mysql的日志吧:

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’objects_summary_global_by_type’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Incorrect definition of table performance_schema.rwlock_instances: expected column ‘WRITE_LOCKED_BY_THREAD_ID’ at position 2 to have type bigint(20), found type int(11).

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’setup_actors’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’setup_objects’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’table_io_waits_summary_by_index_usage’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’table_io_waits_summary_by_table’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’table_lock_waits_summary_by_table’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Column count of mysql.threads is wrong. Expected 14, found 3. Created with MySQL 50524, now running 50623. Please use mysql_upgrade to fix this error.

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’events_stages_current’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’events_stages_history’ has the wrong structure

2015-04-21 14:51:04 18667 [ERROR] Native table ‘performance_schema’.’events_stages_history_long’ has the wrong structure

2015-04-21 15:05:17 7f5997fff700 InnoDB: Error: Table “mysql”.”innodb_table_stats” not found.

2015-04-21 15:05:17 7f5997fff700 InnoDB: Error: Fetch of persistent statistics requested for table “db_anonymous_info_10”.”t_friend_info_3″ but the required system tables mysql.innodb_table_stats and mysql.innodb_index_stats are not present or have unexpected structure. Using transient stats instead.

2015-04-21 15:05:17 7f7beb0cd700 InnoDB: Error: Table “mysql”.”innodb_table_stats” not found.

2015-04-21 15:05:17 7f7beb0cd700 InnoDB: Error: Fetch of persistent statistics requested for table “db_user_trade_1”.”t_trade_15″ but the required system tables mysql.innodb_table_stats and mysql.innodb_index_stats are not present or have unexpected structure. Using transient stats instead.

可以看到,这个实例中,P_S(performanc_schema)库的几个表结构都异常了。另外,mysql.innodb_table_stats表也异常了,导致InnoDB表数据收集异常,然后SQL thread也跟着异常了。

3、问题解决建议

造成上面问题主要原因是,没有用正确的方式来部署slave实例。从master上用xtrabackup物理备份到slave,启动实例后,应该再执行 mysql_upgrade 升级相关表结构,确保P_S(performanc_schema)、I_S(information_schema)以及 mysql 等几个系统库表结构都升级到最新版本。

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