Mess with innodb_thread_concurrency (mysql与多cpu)

以你之姓@ 2022-08-10 13:48 15阅读 0赞

原贴:http://www.mysqlperformanceblog.com/2006/05/12/mess-with-innodb\_thread\_concurrency/

### [Mess with innodb\_thread\_concurrency][Mess with innodb_thread_concurrency] ###

Posted by **Vadim**

In MySQL 5.0.19 the meaning of innodb\_thread\_concurrency variable was changed (yeah, again).

Now innodb\_thread\_concurrency=0 means unlimitied count of concurrent threads inside InnoDB. It’s logical, but there was long way. In MySQL versions below 5.0.8 for unlimited threads you had to set innodb\_thread\_concurrency over 500 (and default value for innodb\_thread\_concurrency was 8 ).

Starting with MySQL 5.0.8, the default value is 20, and concurrency checking will be disabled if the setting is greater than or equal to 20. But due to different bugs, in 5.0.19 the default value is 8 again, and 0 disables concurrency checking.

So if you used innodb\_thread\_concurrency over 500 (or default value in 5.0.8-5.0.18), don’t forget to change it to 0 in new versions, otherwise you can experience leaps of performance.

Posted by **Vadim** @ 2:29 am :: [Innodb][]    
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Related posts: : [InnoDB thread concurrency][]:: [Fixing column encoding mess in MySQL][]:: [MySQL QA Team Benchmarks for MySQL 5.1.30][]:

### 1 Comment [»][Link 1] ###

1.  [1. MySQL Performance Blog » InnoDB thread concurrency][InnoDB thread concurrency]
    
    \[...\] So what is the best value for innodb\_thread\_concurrency? For 1-CPU and 2-CPU I think it can be just disabled (innodb\_thread\_concurrency=0 since 5.0.19, more about default values). \[...\]
    
    Pingback :: June 5, 2006 @ [2:33 am][2_33 am]

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