# System lock on Slave

**URL:** <https://forums.percona.com/t/system-lock-on-slave/2032>\
**Category:** Other MySQL® Questions\
**Created:** [April 6, 2013, 2:08am UTC](https://forums.percona.com/t/system-lock-on-slave/2032 "2013-04-06T02:08:38Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![seagen](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@seagen](https://forums.percona.com/u/seagen)\
**Post date:** [April 6, 2013, 2:08am UTC](https://forums.percona.com/t/system-lock-on-slave/2032/1 "2013-04-06T02:08:38Z")

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## 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.

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<div class="post-metadata">

**Author:** ![niljoshi](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/niljoshi/32/16889_2.png) [@niljoshi](https://forums.percona.com/u/niljoshi)\
**Post date:** [April 10, 2013, 3:28am UTC](https://forums.percona.com/t/system-lock-on-slave/2032/2 "2013-04-10T03:28:21Z")

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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](http://bugs.mysql.com/bug.php?id=68460%5B/URL%5D)

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<div class="post-metadata">

**Author:** ![seagen](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@seagen](https://forums.percona.com/u/seagen)\
**Post date:** [April 10, 2013, 8:42am UTC](https://forums.percona.com/t/system-lock-on-slave/2032/3 "2013-04-10T08:42:51Z")

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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.