剖析MySQL5.6.12 Waiting for commit lock导致从卡死_mysql教程_开发教程

nagios报警，线上一台从库检测不到slave状态，于是远程上去查看问题：

1，show slave status\G卡住：

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show slave status\G

show slave status卡住了，动弹不了，这种情况还是第一次遇到。

2，看w负载无压力：

[root@tmp3_72 ~]# w
 13:23:31 up 828 days, 21:54,  3 users,  load average: 0.08, 0.05, 0.00
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
root     tty1     -                29Sep13 827days  0.15s  0.15s -bash
root     pts/0    192.168.120.28   13:19    3:49   0.18s  0.14s mysql
root     pts/1    192.168.120.28   13:23    0.00s  0.08s  0.02s w
[root@tmp3_72 ~]# 
[root@tmp3_72 ~]# 
[root@tmp3_72 ~]#

3，Top看mysqld进程占据cpu才0.3%

4，查看error日志，没有发现异常记录：

[root@tmp3_72 mysql]# tail -f /usr/local/mysql/mysqld.log 
2015-12-29 20:35:31 29254 [Note]   - '::' resolves to '::';
2015-12-29 20:35:31 29254 [Note] Server socket created on IP: '::'.
2015-12-29 20:35:31 29254 [Note] Event Scheduler: Loaded 0 events
2015-12-29 20:35:31 29254 [Note] /usr/local/mysql/bin/mysqld: ready for connections.
Version: '5.6.12-log'  socket: '/usr/local/mysql/mysql.sock'  port: 3306  Source distribution
2015-12-29 20:35:40 29254 [Note] 'CHANGE MASTER TO executed'. Previous state master_host='', master_port= 3306, master_log_file='', master_log_pos= 4, master_bind=''. New state master_host='', master_port= 3306, master_log_file='mysql-bin.036282', master_log_pos= 120, master_bind=''.
2015-12-30 10:00:04 29254 [Note] 'CHANGE MASTER TO executed'. Previous state master_host='', master_port= 3306, master_log_file='', master_log_pos= 4, master_bind=''. New state master_host='192.168.12.71', master_port= 3306, master_log_file='mysql-bin.036282', master_log_pos= 120, master_bind=''.
2015-12-30 10:00:04 29254 [Note] Slave SQL thread initialized, starting replication in log 'mysql-bin.036282' at position 120, relay log './mysql-relay-bin.000001' position: 4
2015-12-30 10:00:04 29254 [Warning] Storing MySQL user name or password information in the master.info repository is not secure and is therefore not recommended. Please see the MySQL Manual for more about this issue and possible alternatives.
2015-12-30 10:00:04 29254 [Note] Slave I/O thread: connected to master 'repl@192.168.12.71:3306',replication started in log 'mysql-bin.036282' at position 120

5，查看到后台的mysql进程，有一个mysqldump备份进程，执行了很久，我kill掉试试看

[root@tmp3_72 mysql]# ps -eaf|grep mysql
root     16100 16094  0 12:00 ?        00:00:00 /bin/sh -c /home/data/mysql/backup/scripts/backup_full.sh
root     16104 16100  0 12:00 ?        00:00:00 /usr/local/mysql/bin/mysqldump -uroot --password= -R -E -h localhost --skip-opt --single-transaction --flush-logs --master-data=2 --add-drop-table --create-option --quick --extended-insert --set-charset --disable-keys --databases user_db plocc_system parking_db
root     18986 18967  0 13:19 pts/0    00:00:00 mysql
nagios   19486 19485  0 13:33 ?        00:00:00 /usr/local/nagios/libexec/check_mysql -unagios -P3306 -S -s /usr/local/mysql/mysql.sock -Hlocalhost --password=XXXXXXXXXXXX -d test -w 60 -c 100
root     19511 19121  0 13:34 pts/1    00:00:00 grep mysql
root     28242     1  0  2015 ?        00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/home/data/mysql/data --pid-file=/usr/local/mysql/mysqld.pid
mysql    29254 28242  9  2015 ?        16:56:36 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/home/data/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/usr/local/mysql/mysqld.log --open-files-limit=8192 --pid-file=/usr/local/mysql/mysqld.pid --socket=/usr/local/mysql/mysql.sock --port=3306
[root@tmp3_72 mysql]# kill -9 16104
[root@tmp3_72 mysql]# 
[root@tmp3_72 mysql]# 
[root@tmp3_72 mysql]# ps -eaf|grep mysql
root     18986 18967  0 13:19 pts/0    00:00:00 mysql
root     19555 19121  0 13:34 pts/1    00:00:00 grep mysql
root     28242     1  0  2015 ?        00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/home/data/mysql/data --pid-file=/usr/local/mysql/mysqld.pid
mysql    29254 28242  9  2015 ?        16:56:36 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/home/data/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/usr/local/mysql/mysqld.log --open-files-limit=8192 --pid-file=/usr/local/mysql/mysqld.pid --socket=/usr/local/mysql/mysql.sock --port=3306
[root@tmp3_72 mysql]#

6，kill掉备份进程后，执行一条简单的delete语句，会卡住，看来kill解决不了问题

mysql> select * from test;
+------+------+
| id   | name |
+------+------+
|    0 | NULL |
|    1 | NULL |
|    2 | NULL |
|    3 | NULL |
+------+------+
4 rows in set (0.02 sec)

mysql> 
mysql> 
mysql> delete from test where id=0;

去查询当前进程：

mysql> select User,State,count(1) from information_schema.processlist group by User,State;
+--------------+----------------------------------------+----------+
| User         | State                                  | count(1) |
+--------------+----------------------------------------+----------+
| cacti_user   |                                        |       17 |
| cacti_user   | executing                              |      657 |
| nagios       | executing                              |       38 |
| ploccsys_web |                                        |       10 |
| root         | executing                              |        1 |
| root         | init                                   |        2 |
| system user  | Queueing master event to the relay log |        1 |
| system user  | Waiting for commit lock                |        1 |
+--------------+----------------------------------------+----------+
8 rows in set (0.01 sec)

mysql>

有许多类似下面的线程：

| 516544 | cacti_user   | 192.168.11.12:42082 | NULL         | Query   |    375 | executing                              | SHOW /*!50002 GLOBAL */ STATUS |
| 516564 | cacti_user   | 192.168.11.12:42208 | NULL         | Query   |    350 | executing                              | SHOW /*!50002 GLOBAL */ STATUS |
| 516571 | cacti_user   | 192.168.11.12:42215 | NULL         | Query   |    330 | executing                              | SHOW /*!50002 GLOBAL */ STATUS |
| 516575 | cacti_user   | 192.168.11.12:42218 | NULL         | Query   |    320 | executing                              | SHOW /*!50002 GLOBAL */ STATUS |
| 516592 | cacti_user   | 192.168.11.12:42230 | NULL         | Query   |    315 | executing                              | SHOW /*!50002 GLOBAL */ STATUS |
| 516598 | cacti_user   | 192.168.11.12:42359 | NULL         | Query   |    300 | executing                              | SHOW /*!50002 GLOBAL */ STATUS |

要不要重启mysql db或者是重启cacti服务器？想来还是继续再看看，万不得已不能用绝招。^_^

7，写了个脚本来kill这些来自cacti的show status的线程

[root@tmp3_72 scripts]# vim killsleep_cacti.sh 

#It is used to kill processlist of mysql sleep
#!/bin/sh
while :

do
  n=`mysqladmin processlist -uroot --password=""|grep -i sleep |wc -l`
  date=`date +%Y%m%d\[%H:%M:%S]`
  echo $n

  if [ "$n" -gt 10 ]
  then
  echo "begin kill the sleep processlist ......"
  for i in `mysqladmin processlist -uroot --password=""|grep -i sleep |awk '{print $2}'`
  do
     mysqladmin -uroot --password="" kill $i
  done
  echo "begin kill the executing cacti show status processlist ......"
  for i in `mysqladmin processlist -uroot --password=""|grep -i executing |grep -i SHOW|grep -i STATUS |grep -i cacti |awk '{print $2}'`
  do
     mysqladmin -uroot --password="" kill $i
  done

  echo "sleep is too many I killed it " >> /tmp/sleep.log
  echo "$date : $n" >> /tmp/sleep.log
  fi
  sleep 1
done

执行后，通过show full processlist;这些线程仍然存在，只是状态从excuteing变成了killed而已：其它问题仍然没有改观

mysql> select User,Command,count(1) from information_schema.processlist group by User,Command;
+--------------+---------+----------+
| User         | Command | count(1) |
+--------------+---------+----------+
| cacti_user   | Killed  |      792 |
| cacti_user   | Query   |        4 |
| cacti_user   | Sleep   |        1 |
| nagios       | Query   |       48 |
| ploccsys_web | Sleep   |       10 |
| root         | Killed  |        1 |
| root         | Query   |        2 |
| root         | Refresh |        1 |
| system user  | Connect |        2 |
+--------------+---------+----------+
9 rows in set (0.01 sec)

mysql>

7，重新查看slave状态，还是无效

mysql> show slave status\G
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    523275
Current database: test

8，去查看engine状态

mysql> show engine innodb status\G
*************************** 1. row ***************************
  Type: InnoDB
  Name: 
Status: 
=====================================
2016-01-06 15:08:52 7f3ef5a19700 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 50 seconds
-----------------
BACKGROUND THREAD
-----------------
srv_master_thread loops: 475489 srv_active, 0 srv_shutdown, 195322 srv_idle
srv_master_thread log flush and writes: 670800
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 697461
OS WAIT ARRAY INFO: signal count 710269
Mutex spin waits 2340260, rounds 18635522, OS waits 498279
RW-shared spins 132111, rounds 3631441, OS waits 119612
RW-excl spins 25200, rounds 2213112, OS waits 70336
Spin rounds per wait: 7.96 mutex, 27.49 RW-shared, 87.82 RW-excl
------------
TRANSACTIONS
------------
Trx id counter 1247855846
Purge done for trx's n:o < 1247855835 undo n:o < 0 state: running but idle
History list length 2442
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 0, not started
MySQL thread id 523731, OS thread handle 0x7f3ef5a19700, query id 150089612 localhost root init
show engine innodb status
---TRANSACTION 0, not started
MySQL thread id 522540, OS thread handle 0x7f3ef7ea8700, query id 150086762 localhost root executing
SHOW /*!50002 GLOBAL */ STATUS
---TRANSACTION 1247853306, not started
MySQL thread id 35671, OS thread handle 0x7f4bf8083700, query id 0 Queueing master event to the relay log
---TRANSACTION 1247855447, ACTIVE 11330 sec
mysql tables in use 1, locked 1
2 lock struct(s), heap size 376, 1 row lock(s), undo log entries 1
MySQL thread id 35672, OS thread handle 0x7f4bf8052700, query id 150059111 Waiting for commit lock
--------
FILE I/O
--------
I/O thread 0 state: waiting for i/o request (insert buffer thread)
I/O thread 1 state: waiting for i/o request (log thread)
I/O thread 2 state: waiting for i/o request (read thread)
I/O thread 3 state: waiting for i/o request (read thread)
I/O thread 4 state: waiting for i/o request (read thread)
I/O thread 5 state: waiting for i/o request (read thread)
I/O thread 6 state: waiting for i/o request (write thread)
I/O thread 7 state: waiting for i/o request (write thread)
I/O thread 8 state: waiting for i/o request (write thread)
I/O thread 9 state: waiting for i/o request (write thread)
Pending normal aio reads: 0 [0, 0, 0, 0] , aio writes: 0 [0, 0, 0, 0] ,
 ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0
Pending flushes (fsync) log: 0; buffer pool: 0
9067 OS file reads, 129305477 OS file writes, 12754944 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 11, seg size 13, 0 merges
merged operations:
 insert 0, delete mark 0, delete 0
discarded operations:
 insert 0, delete mark 0, delete 0
Hash table size 75692179, node heap has 2437 buffer(s)
0.00 hash searches/s, 0.00 non-hash searches/s
---
LOG
---
Log sequence number 418264709881
Log flushed up to   418264709881
Pages flushed up to 418264709881
Last checkpoint at  418264709881
0 pending log writes, 0 pending chkp writes
110060310 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total memory allocated 35165044736; in additional pool allocated 0
Dictionary memory allocated 1420595
Buffer pool size   2097144
Free buffers       1375231
Database pages     719476
Old database pages 265424
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 1474, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 91286, created 628190, written 34807582
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 719476, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
----------------------
INDIVIDUAL BUFFER POOL INFO
----------------------
---BUFFER POOL 0
Buffer pool size   262143
Free buffers       172002
Database pages     89836
Old database pages 33142
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 97, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 11534, created 78302, written 5644943
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 89836, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 1
Buffer pool size   262143
Free buffers       171914
Database pages     89924
Old database pages 33174
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 259, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 11425, created 78499, written 3352647
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 89924, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 2
Buffer pool size   262143
Free buffers       171570
Database pages     90267
Old database pages 33301
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 158, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 11720, created 78547, written 2182721
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 90267, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 3
Buffer pool size   262143
Free buffers       172120
Database pages     89724
Old database pages 33100
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 141, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 11117, created 78607, written 8155448
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 89724, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 4
Buffer pool size   262143
Free buffers       171665
Database pages     90167
Old database pages 33264
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 142, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 11675, created 78492, written 7450709
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 90167, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 5
Buffer pool size   262143
Free buffers       172081
Database pages     89746
Old database pages 33108
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 185, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 11258, created 78488, written 3505157
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 89746, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 6
Buffer pool size   262143
Free buffers       173275
Database pages     88569
Old database pages 32674
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 336, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 10622, created 77947, written 2488265
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 88569, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
---BUFFER POOL 7
Buffer pool size   262143
Free buffers       170604
Database pages     91243
Old database pages 33661
Modified db pages  0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages made young 156, not young 0
0.00 youngs/s, 0.00 non-youngs/s
Pages read 11935, created 79308, written 2027692
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
Pages read ahead 0.00/s, evicted without access 0.00/s, Random read ahead 0.00/s
LRU len: 91243, unzip_LRU len: 0
I/O sum[0]:cur[0], unzip sum[0]:cur[0]
--------------
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
0 read views open inside InnoDB
Main thread process no. 29254, id 139925894604544, state: sleeping
Number of rows inserted 71967166, updated 94419979, deleted 45975, read 7366029184
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================

1 row in set (0.02 sec)

mysql>

9，去查看是否有locks信息

mysql> select * from information_schema.INNODB_TRX\G;
*************************** 1. row ***************************
                    trx_id: 1247855447
                 trx_state: RUNNING
               trx_started: 2016-01-06 12:00:02
     trx_requested_lock_id: NULL
          trx_wait_started: NULL
                trx_weight: 3
       trx_mysql_thread_id: 35672
                 trx_query: NULL
       trx_operation_state: NULL
         trx_tables_in_use: 1
         trx_tables_locked: 1
          trx_lock_structs: 2
     trx_lock_memory_bytes: 376
           trx_rows_locked: 1
         trx_rows_modified: 1
   trx_concurrency_tickets: 0
       trx_isolation_level: READ COMMITTED
         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
          trx_is_read_only: 0
trx_autocommit_non_locking: 0
1 row in set (0.00 sec)

ERROR: 
No query specified

mysql>

mysql> select * from INNODB_LOCKS;
Empty set (0.00 sec)

mysql> 
mysql> 
mysql> 
mysql> select * from INNODB_LOCK_WAITS;
Empty set (0.00 sec)

mysql>

有一个事务是running状态，根据trx_mysql_thread_id: 35672查询processlist表:

mysql> select * from processlist where id=35672;
+-------+-------------+------+------+---------+-------+-------------------------+------+
| ID    | USER        | HOST | DB   | COMMAND | TIME  | STATE                   | INFO |
+-------+-------------+------+------+---------+-------+-------------------------+------+
| 35672 | system user |      | NULL | Connect | 11948 | Waiting for commit lock | NULL |
+-------+-------------+------+------+---------+-------+-------------------------+------+
1 row in set (0.01 sec)

mysql>

正常的从服务器是：

mysql> select * from processlist order by id limit 2;
+----------+-------------+------+------+---------+--------+------------------------------------------------------------------+------+
| ID       | USER        | HOST | DB   | COMMAND | TIME   | STATE                                                            | INFO |
+----------+-------------+------+------+---------+--------+------------------------------------------------------------------+------+
| 29903251 | system user |      | NULL | Connect | 624229 | Waiting for master to send event                                 | NULL |
| 29903252 | system user |      | NULL | Connect |      5 | Slave has read all relay log; waiting for the slave I/O thread t | NULL |
+----------+-------------+------+------+---------+--------+------------------------------------------------------------------+------+
2 rows in set (0.00 sec)

mysql>

而我的这台出故障的从服务器是：

mysql> select * from processlist order by id limit 2;
+-------+-------------+------+------+---------+--------+----------------------------------------+------+
| ID    | USER        | HOST | DB   | COMMAND | TIME   | STATE                                  | INFO |
+-------+-------------+------+------+---------+--------+----------------------------------------+------+
| 35671 | system user |      | NULL | Connect | 624374 | Queueing master event to the relay log | NULL |
| 35672 | system user |      | NULL | Connect |  12379 | Waiting for commit lock                | NULL |
+-------+-------------+------+------+---------+--------+----------------------------------------+------+
2 rows in set (0.01 sec)

mysql>

再次查看统计，确定问题所在为system user | Connect | Waiting for commit lock 线程导致：

mysql> select User,Command,State,count(1) from information_schema.processlist group by User,Command,State;
+--------------+---------+----------------------------------------+----------+
| User         | Command | State                                  | count(1) |
+--------------+---------+----------------------------------------+----------+
| cacti_user   | Killed  | executing                              |      792 |
| cacti_user   | Query   | executing                              |      344 |
| nagios       | Query   | executing                              |       72 |
| ploccsys_web | Sleep   |                                        |       10 |
| root         | Killed  | executing                              |        1 |
| root         | Killed  | init                                   |        5 |
| root         | Query   | executing                              |        1 |
| root         | Query   | Waiting for table flush                |        1 |
| root         | Refresh | init                                   |        1 |
| system user  | Connect | Queueing master event to the relay log |        1 |
| system user  | Connect | Waiting for commit lock                |        1 |
+--------------+---------+----------------------------------------+----------+
11 rows in set (0.02 sec)

mysql>

10，问题解决

事情到此地步，已经很明确了就是Waiting for commit lock 这个导致的全局锁，所以kill掉innodb_trx中的running事务的mysql线程：

mysql> kill 35672
    -> ;
Query OK, 0 rows affected (0.00 sec)

mysql>

然后再去check processlist；已经正常了，如下所示：

mysql> show full processlist;
+--------+--------------+-------------------+--------------------+---------+-------+----------------------------------+-----------------------+
| Id     | User         | Host              | db                 | Command | Time  | State                            | Info                  |
+--------+--------------+-------------------+--------------------+---------+-------+----------------------------------+-----------------------+
| 527023 | root         | localhost         | information_schema | Query   |     0 | init                             | show full processlist |
| 527165 | system user  |                   | NULL               | Connect |    54 | Waiting for master to send event | NULL                  |
| 527166 | system user  |                   | NULL               | Connect | 12548 | System lock                      | NULL                  |
| 527167 | ploccsys_web | 192.168.12.28:33006 | plocc_system       | Sleep   |    28 |                                  | NULL                  |
| 527168 | ploccsys_web | 192.168.12.28:33007 | plocc_system       | Sleep   |    28 |                                  | NULL                  |
| 527169 | ploccsys_web | 192.168.12.28:33008 | plocc_system       | Sleep   |    28 |                                  | NULL                  |
| 527170 | ploccsys_web | 192.168.12.28:33009 | plocc_system       | Sleep   |    28 |                                  | NULL                  |
| 527171 | ploccsys_web | 192.168.12.28:33010 | plocc_system       | Sleep   |    28 |                                  | NULL                  |
| 527172 | ploccsys_web | 192.168.12.29:43473 | plocc_system       | Sleep   |    16 |                                  | NULL                  |
| 527173 | ploccsys_web | 192.168.12.29:43474 | plocc_system       | Sleep   |    16 |                                  | NULL                  |
| 527174 | ploccsys_web | 192.168.12.29:43476 | plocc_system       | Sleep   |    16 |                                  | NULL                  |
| 527175 | ploccsys_web | 192.168.12.29:43477 | plocc_system       | Sleep   |    16 |                                  | NULL                  |
| 527176 | ploccsys_web | 192.168.12.29:43478 | plocc_system       | Sleep   |    16 |                                  | NULL                  |
+--------+--------------+-------------------+--------------------+---------+-------+----------------------------------+-----------------------+
13 rows in set (0.00 sec)

mysql>

在查看slave状态，是No状态，如下所示：

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 192.168.12.71
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.037579
          Read_Master_Log_Pos: 2172311
               Relay_Log_File: mysql-relay-bin.002685
                Relay_Log_Pos: 13453336
        Relay_Master_Log_File: mysql-bin.037578
             Slave_IO_Running: No
            Slave_SQL_Running: No
              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: 13453173
              Relay_Log_Space: 15626372
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: NULL
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: 71
                  Master_UUID: 9b0dcf62-29f4-11e3-9471-677b33903869
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: 
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 
            Executed_Gtid_Set: 
                Auto_Position: 0
1 row in set (0.00 sec)

mysql>

之后启动slave，start slave;搞定。

11，网友 Aeolus@普的提示

DEADLOCK ON FLUSH TABLES WITH READ LOCK + SHOW SLAVE STATUS Problem: If a client thread on an slave does FLUSH TABLES WITH READ LOCK; then master does some updates, SHOW SLAVE STATUS in the same client will be blocked. Analysis: Execute FLUSH TABLES WITH READ LOCK on slave and at the same time execute a DML on the master. Then the DML should be made to stop at a state “Waiting for commit lock”. This state means that sql thread is holding rli->data_lock and waiting for MDL_COMMIT lock. Now in the same client session where FLUSH TABLES WITH READ LOCK was executed issue SHOW SLAVE STATUS command. This command will be blocked waiting for rli->data_lock causing a dead lock. Once this happens it will not be possible to release the global read lock as “UNLOCK TABLES” command has to be issued in the same client where global read lock was acquired. This causes the dead lock. Fix: Existing code holds the rli->data_lock for the whole duration of commit operation. Instead of holding the lock for entire commit duration the code has been restructured in such a way that the lock is held only during the period when rli object is being updated.

然后去查了下我这台db从服务器，确实有每我这台从库是有做mysqldump备份的，一个小时备份一次，然后cacti监控也会每分钟就来抽取一次数据，可能还真的是 mysqldump+cacti的show slave status一起执行导致的bug 出现。我先去将备份改成4个小时一次，继续观察后续情况。

(责任编辑：最模板)