seagen
1
Version Info:
MySQL 5.6.10 on ext3
CentOS 6.3 2.6.32-279.el6.x86_64
Cloud Server (aliyun)
On Slave:
sql> show slave status\G
…
Slave_SQL_Running_State: System lock
…
sql> select name,PROCESSLIST_STATE,PROCESSLIST_INFO from performance_schema.threads;
…
thread/sql/main | System lock | INTERNAL DDL LOG RECOVER IN PROGRESS
thread/sql/slave_sql | System lock | NULL
skip_external_lock = on
My question:
What causes system lock on sql thread? But I found that my replication is still working normally.
Hi,
Can you provide output of show full processlist when you are getting above error? It may be something like [URL]MySQL Bugs: #68460: blocked with FLUSH TABLES WITH READ LOCK + SHOW SLAVE STATUS
seagen
3
Thanks,dude 
mysql> show full processlist;
±------±------------±----------±-----±--------±------- ±---------------------------------±----------------------+
| Id | User | Host | db | Command | Time | State | Info |
±------±------------±----------±-----±--------±------- ±---------------------------------±----------------------+
| 11166 | root | localhost | NULL | Query | 0 | init | show full processlist |
| 11167 | system user | | NULL | Connect | 80 | Waiting for master to send event | NULL |
| 11168 | system user | | NULL | Connect | 362900 | System lock | NULL |
±------±------------±----------±-----±--------±------- ±---------------------------------±----------------------+
From my point it does not look like a bug. Actually,I could not find any locks on mysqld and right now my replicas is working well.