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记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

WBOY
發布： 2016-06-07 15:20:48
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记一次 数据库 调优 过程 （IIS发 过来 SQLSERVER 的FETCH API_CURSOR语句是神马？） 前几天帮客户优化一个 数据库 ，那个 数据库 的大小是6G 这麽小的 数据库 按道理不会有太大的性能问题的，但是客户反应说CPU占用很高，经常达到 80%~90% 我检查了任务管理

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API_CURSOR语句是神马？）

前几天帮客户优化一个数据库，那个数据库的大小是6G

这麽小的数据库按道理不会有太大的性能问题的，但是客户反应说CPU占用很高，经常达到80%~90%

我检查了任务管理器，确实是SQLSERVER占的CPU

而服务器的内存是16G内存，只占用了7G+

客户的环境：

Windows2008R2

SQLSERVER2005 SP3 64位 企业版

服务器内存：16G

CPU：8核

RDS:阿里云主机

IIS7.5

网站使用ASP技术

 

着手查找原因

于是就着手检查占用CPU高的原因，检查了很久，发现有一些SQL语句占用CPU很高，而执行的SQL语句如下：

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

 

 这些是什么语句呢？在msdn上面找不到任何资料，使用下面的SQL语句查看，在[program_name]字段可以看到是IIS发过来的

<span>SELECT</span> <span>*</span> <span>FROM</span> sys.<span>[</span><span>sysprocesses</span><span>]</span> <span>WHERE</span> SPID<span>>=</span><span>50</span>
登入後複製
登入後複製

难道是IIS的bug？然后我又继续在茫茫网海里查找资料，最后终于在paul的博客里找到原因

文章地址：Hunting down the origins of FETCH API_CURSOR and sp_cursorfetch

文章大意

我在调优数据库的时候，使用sqlserver profiler捕获RPC:Completed 事件，可以看到很多类似下面的语句

exec sp_cursorfetch 180150003,32,1,1
exec sp_cursorfetch 180150003,32,1,1
exec sp_cursorfetch 180150003,32,1,1
exec sp_cursorfetch 180150003,32,1,1

 

你看到这些语句是从session_id为53的session那里发过来的

于是用下面语句看一下session_id为53执行的究竟是什么语句

<span>DBCC</span> INPUTBUFFER (<span>53</span>)
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而返回的结果是

 <span>FETCH</span> API_CURSOR0000000000000004
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您很快意识到这跟服务器游标有一定的关系

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

 

如果你使用sys.dm_exec_requests 视图或者sys.dm_exec_connections视图来查看session_id53执行了什么语句

和执行的状态

<span>SELECT</span> t.<span>text</span>
<span>FROM</span><span> sys.dm_exec_connections c
</span><span>CROSS</span><span> APPLY sys.dm_exec_sql_text (c.most_recent_sql_handle) t
</span><span>WHERE</span> session_id <span>=</span> <span>53</span>
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但是返回的结果依然是

<span>FETCH</span> API_CURSOR0000000000000004
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那么还有没有其他的视图来帮助我们呢？我们可以使用sys.dm_exec_cursors视图，将spid代入进去

<span>SELECT</span> c.session_id, c.properties, c.creation_time, c.is_open, t.<span>text</span>
<span>FROM</span> sys.dm_exec_cursors (<span>53</span><span>) c
</span><span>CROSS</span> APPLY sys.dm_exec_sql_text (c.sql_handle) t
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记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

从结果来看，我们知道语句使用了游标，并且知道游标的属性（scroll locks）和游标创建时间

并且我们看到执行的SQL语句不像是FETCH API_CURSOR或者sp_cursorfetch，而是

<span>SELECT</span> <span>*</span> <span>FROM</span> dbo.FactResellerSales.
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本人的处理过程

1、先使用下面的SQL语句找出当前实例下有使用到游标的语句

<span>--</span><span> =============================================</span><span>
--</span><span> Author:      </span><span>
--</span><span> Blog:        <http:></http:></span><span>
--</span><span> Create date: </span><span>
--</span><span> Description: </span><span>
--</span><span> =============================================</span>
<span>DECLARE</span> <span>@spid</span> <span>NVARCHAR</span>(<span>100</span><span>)
</span><span>DECLARE</span> <span>@SQL</span> <span>NVARCHAR</span>(<span>MAX</span><span>)

</span><span>DECLARE</span> CurSPID <span>CURSOR</span>
<span>FOR</span>
    <span>SELECT</span>  <span>[</span><span>spid</span><span>]</span>
    <span>FROM</span>    sys.<span>[</span><span>sysprocesses</span><span>]</span>
    <span>WHERE</span>   <span>[</span><span>spid</span><span>]</span> <span>>=</span> <span>50</span>

<span>OPEN</span><span> CurSPID
</span><span>FETCH</span> <span>NEXT</span> <span>FROM</span> CurSPID <span>INTO</span> <span>@spid</span>

<span>WHILE</span> <span>@@FETCH_STATUS</span> <span>=</span> <span>0</span>
    <span>BEGIN</span>  
        <span>SET</span> <span>@SQL</span> <span>=</span> N<span>'</span><span>
SELECT  cursors.session_id ,
        cursors.properties ,
        cursors.creation_time ,
        cursors.is_open ,
        text.text
FROM    sys.dm_exec_cursors (</span><span>'</span> <span>+</span> <span>@spid</span> <span>+</span> <span>'</span><span>) cursors
        CROSS APPLY sys.dm_exec_sql_text(cursors.sql_handle) text</span><span>'</span>
        <span>EXEC</span>(<span>@SQL</span><span>) 

        </span><span>FETCH</span> <span>NEXT</span> <span>FROM</span> CurSPID <span>INTO</span> <span>@spid</span>
    <span>END</span>
<span>CLOSE</span><span> CurSPID
</span><span>DEALLOCATE</span> CurSPID
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为什麽上面的脚本要使用游标，因为当时我根据paul的脚本来执行的时候，在活动监视器里能看到使用游标的SQL语句，

但是在SSMS里查询的时候，怎麽也查询不出来，所以才用游标，将使用到游标的语句一网打尽，这里输出的结果要忽略本身这个脚本使用到的游标！！

 

2、根据输出的结果，发现有几个地方使用了游标，下面只是部分截图

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

 

3、把结果拷贝出来，可以发现也是执行的是SELECT 语句

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

 

4、因为是ASP程序，没有用到存储过程，于是搜索项目文件，看一下哪个文件有类似的代码

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

5、找到结果

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

 记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

ASP的语法跟VB是很像的，本人觉得非常羞涩

可以看到server对象创建了一个recordset对象，然后从recordset对象里逐条记录取出来，再做处理，可以看到后续还有

select case....case...case....

就是对取出来的记录再做处理

 

因为ASP是脚本语言，由IIS来执行，所以在SQLSERVER这边可以看到下面语句的program_name字段是IIS

<span>SELECT</span> <span>*</span> <span>FROM</span> sys.<span>[</span><span>sysprocesses</span><span>]</span> <span>WHERE</span> SPID<span>>=</span><span>50</span>
登入後複製
登入後複製

 

6、验证一下是否是游标的原因导致CPU高，使用下面的脚本

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API 

<span>SELECT</span> <span>*</span> <span>FROM</span> sys.<span>[</span><span>dm_os_performance_counters</span><span>]</span> 
<span>WHERE</span> <span>[</span><span>counter_name</span><span>]</span><span>=</span><span>'</span><span>CPU usage %</span><span>'</span>   
<span>AND</span> <span>[</span><span>object_name</span><span>]</span><span>=</span><span>'</span><span>SQLServer:Resource Pool Stats</span><span>'</span>     
<span>AND</span> <span>[</span><span>instance_name</span><span>]</span><span>=</span><span>'</span><span>default</span><span>'</span>                                                


<span>SELECT</span> <span>*</span> <span>FROM</span> sys.<span>[</span><span>dm_os_performance_counters</span><span>]</span> 
<span>WHERE</span> <span>[</span><span>counter_name</span><span>]</span><span>=</span><span>'</span><span>Active cursors</span><span>'</span>   
<span>AND</span> <span>[</span><span>object_name</span><span>]</span><span>=</span><span>'</span><span>SQLServer:Cursor Manager by Type</span><span>'</span>     
<span>AND</span> <span>[</span><span>instance_name</span><span>]</span><span>=</span><span>'</span><span>_Total</span><span>'</span>                                                


<span>--</span><span>建表</span>
<span>USE</span> <span>[</span><span>msdb</span><span>]</span>
<span>GO</span>
<span>CREATE</span> <span>TABLE</span><span> ActiveCursors
(cntr_value </span><span>BIGINT</span>,cntr_time <span>DATETIME</span> <span>PRIMARY</span> <span>KEY</span><span>)
</span><span>GO</span>
<span>CREATE</span> <span>TABLE</span><span> CPUUsage
(cntr_value </span><span>BIGINT</span>,cntr_time <span>DATETIME</span> <span>PRIMARY</span> <span>KEY</span><span>)
</span><span>GO</span>


<span>--</span><span>建作业</span>
<span>DECLARE</span> <span>@DBName</span> <span>NVARCHAR</span>(<span>MAX</span><span>)
</span><span>DECLARE</span> <span>@job_name</span><span> sysname

</span><span>SET</span> <span>@DBName</span><span>=</span><span>'</span><span>xxx</span><span>'</span>  <span>--</span><span>★Do</span>

<span>SET</span> <span>@job_name</span><span>=</span><span>'</span><span>Monitor_CPUUsage_</span><span>'</span> <span>+</span> <span>@DBName</span>
<span>EXEC</span> msdb.dbo.sp_add_job <span>@job_name</span><span>=</span><span>@job_name</span><span>, 
</span><span>@enabled</span><span>=</span><span>1</span><span>, 
</span><span>@notify_level_eventlog</span><span>=</span><span>0</span><span>, 
</span><span>@notify_level_email</span><span>=</span><span>0</span><span>, 
</span><span>@notify_level_netsend</span><span>=</span><span>0</span><span>, 
</span><span>@notify_level_page</span><span>=</span><span>0</span><span>, 
</span><span>@delete_level</span><span>=</span><span>0</span><span>, 
</span><span>@description</span><span>=</span>N<span>'</span><span>监控CPU使用率</span><span>'</span><span>, 
</span><span>@category_name</span><span>=</span>N<span>'</span><span>Database Maintenance</span><span>'</span><span>, 
</span><span>@owner_login_name</span><span>=</span>N<span>'</span><span>sa</span><span>'</span> 


<span>--</span><span>添加监控步骤</span>
<span>DECLARE</span> <span>@job_name</span><span> SYSNAME
</span><span>DECLARE</span> <span>@SQL</span> <span>NVARCHAR</span>(<span>MAX</span><span>)
</span><span>DECLARE</span> <span>@DBName</span> <span>NVARCHAR</span>(<span>MAX</span><span>)

</span><span>SET</span> <span>@DBName</span><span>=</span><span>'</span><span>xxx</span><span>'</span>  <span>--</span><span>★Do</span>
<span>SET</span> <span>@job_name</span><span>=</span><span>'</span><span>Monitor_CPUUsage_</span><span>'</span> <span>+</span> <span>@DBName</span>  <span>--</span><span>★Do</span>

<span>BEGIN</span> 
    <span>SET</span> <span>@SQL</span> <span>=</span> N<span>'</span><span>
USE [msdb]
GO
INSERT INTO CPUUsage(cntr_value,cntr_time)  
SELECT cntr_value,GETDATE() FROM sys.[dm_os_performance_counters] 
WHERE [counter_name]=</span><span>''</span><span>CPU usage %</span><span>''</span><span>   
AND [object_name]=</span><span>''</span><span>SQLServer:Resource Pool Stats</span><span>''</span><span>   
AND [instance_name]=</span><span>''</span><span>default</span><span>''</span>
<span>'</span>
    <span>EXEC</span> msdb.dbo.sp_add_jobstep <span>@job_name</span> <span>=</span> <span>@job_name</span><span>,
        </span><span>@step_name</span> <span>=</span> N<span>'</span><span>Monitor</span><span>'</span>, <span>@step_id</span> <span>=</span> <span>1</span>, <span>@cmdexec_success_code</span> <span>=</span> <span>0</span><span>,
        </span><span>@on_success_action</span> <span>=</span> <span>3</span>, <span>@on_success_step_id</span> <span>=</span> <span>0</span>, <span>@on_fail_action</span> <span>=</span> <span>2</span><span>,
        </span><span>@on_fail_step_id</span> <span>=</span> <span>0</span>, <span>@retry_attempts</span> <span>=</span> <span>0</span>, <span>@retry_interval</span> <span>=</span> <span>0</span><span>,
        </span><span>@os_run_priority</span> <span>=</span> <span>0</span>, <span>@subsystem</span> <span>=</span> N<span>'</span><span>TSQL</span><span>'</span>, <span>@command</span> <span>=</span> <span>@SQL</span><span>,
        </span><span>@database_name</span> <span>=</span> <span>@DBNAME</span>, <span>@flags</span> <span>=</span> <span>0</span>

<span>END</span>

  


<span>--</span><span>创建Monitor作业的调度计划</span>
<span>DECLARE</span> <span>@job_name</span><span> SYSNAME
</span><span>DECLARE</span> <span>@SQL</span> <span>NVARCHAR</span>(<span>MAX</span><span>)
</span><span>DECLARE</span> <span>@DBName</span> <span>NVARCHAR</span>(<span>MAX</span><span>)

</span><span>SET</span> <span>@DBName</span><span>=</span><span>'</span><span>xxx</span><span>'</span>  <span>--</span><span>★Do</span>
<span>SET</span> <span>@job_name</span><span>=</span><span>'</span><span>Monitor_CPUUsage_</span><span>'</span> <span>+</span> <span>@DBName</span>  <span>--</span><span>★Do</span>

<span>--</span><span>修改作业的执行时间</span>
<span>EXEC</span>  msdb.dbo.sp_add_jobschedule  <span>@job_name</span> <span>=</span> <span>@job_name</span>, <span>@name</span><span>=</span>N<span>'</span><span>Plan</span><span>'</span><span>, 
        </span><span>@enabled</span><span>=</span><span>1</span><span>, 
        </span><span>@freq_type</span><span>=</span><span>4</span><span>, 
        </span><span>@freq_interval</span><span>=</span><span>1</span><span>, 
        </span><span>@freq_subday_type</span><span>=</span><span>2</span><span>, 
        </span><span>@freq_subday_interval</span><span>=</span><span>30</span><span>, 
        </span><span>@freq_relative_interval</span><span>=</span><span>0</span><span>, 
        </span><span>@freq_recurrence_factor</span><span>=</span><span>0</span><span>, 
        </span><span>@active_start_date</span><span>=</span><span>20140105</span><span>, 
        </span><span>@active_end_date</span><span>=</span><span>99991231</span><span>, 
        </span><span>@active_start_time</span><span>=</span><span>2000</span><span>, 
        </span><span>@active_end_time</span><span>=</span><span>235959</span>

<span>EXEC</span>  msdb.dbo.sp_add_jobserver  <span>@job_name</span> <span>=</span> <span>@job_name</span>, <span>@server_name</span> <span>=</span> N<span>'</span><span>(local)</span><span>'</span>





<span>--</span><span>----------------------------------------------------------------------------</span><span>
--</span><span>建作业</span>
<span>DECLARE</span> <span>@DBName</span> <span>NVARCHAR</span>(<span>MAX</span><span>)
</span><span>DECLARE</span> <span>@job_name</span><span> sysname

</span><span>SET</span> <span>@DBName</span><span>=</span><span>'</span><span>xxx</span><span>'</span>  <span>--</span><span>★Do</span>

<span>SET</span> <span>@job_name</span><span>=</span><span>'</span><span>Monitor_ActiveCursors_</span><span>'</span> <span>+</span> <span>@DBName</span>
<span>EXEC</span> msdb.dbo.sp_add_job <span>@job_name</span><span>=</span><span>@job_name</span><span>, 
</span><span>@enabled</span><span>=</span><span>1</span><span>, 
</span><span>@notify_level_eventlog</span><span>=</span><span>0</span><span>, 
</span><span>@notify_level_email</span><span>=</span><span>0</span><span>, 
</span><span>@notify_level_netsend</span><span>=</span><span>0</span><span>, 
</span><span>@notify_level_page</span><span>=</span><span>0</span><span>, 
</span><span>@delete_level</span><span>=</span><span>0</span><span>, 
</span><span>@description</span><span>=</span>N<span>'</span><span>监控游标使用</span><span>'</span><span>, 
</span><span>@category_name</span><span>=</span>N<span>'</span><span>Database Maintenance</span><span>'</span><span>, 
</span><span>@owner_login_name</span><span>=</span>N<span>'</span><span>sa</span><span>'</span> 


<span>--</span><span>添加监控步骤</span>
<span>DECLARE</span> <span>@job_name</span><span> SYSNAME
</span><span>DECLARE</span> <span>@SQL</span> <span>NVARCHAR</span>(<span>MAX</span><span>)
</span><span>DECLARE</span> <span>@DBName</span> <span>NVARCHAR</span>(<span>MAX</span><span>)

</span><span>SET</span> <span>@DBName</span><span>=</span><span>'</span><span>xxxx</span><span>'</span>  <span>--</span><span>★Do</span>
<span>SET</span> <span>@job_name</span><span>=</span><span>'</span><span>Monitor_ActiveCursors_</span><span>'</span> <span>+</span> <span>@DBName</span>  <span>--</span><span>★Do</span>

<span>BEGIN</span> 
    <span>SET</span> <span>@SQL</span> <span>=</span> N<span>'</span><span>
USE [msdb]
GO
INSERT INTO ActiveCursors(cntr_value,cntr_time)  
SELECT cntr_value,GETDATE()  FROM sys.[dm_os_performance_counters] 
WHERE [counter_name]=</span><span>''</span><span>Active cursors</span><span>''</span><span>   
AND [object_name]=</span><span>''</span><span>SQLServer:Cursor Manager by Type</span><span>''</span><span>  
AND [instance_name]=</span><span>''</span><span>_Total</span><span>''</span>
<span>'</span>
    <span>EXEC</span> msdb.dbo.sp_add_jobstep <span>@job_name</span> <span>=</span> <span>@job_name</span><span>,
        </span><span>@step_name</span> <span>=</span> N<span>'</span><span>Monitor</span><span>'</span>, <span>@step_id</span> <span>=</span> <span>1</span>, <span>@cmdexec_success_code</span> <span>=</span> <span>0</span><span>,
        </span><span>@on_success_action</span> <span>=</span> <span>3</span>, <span>@on_success_step_id</span> <span>=</span> <span>0</span>, <span>@on_fail_action</span> <span>=</span> <span>2</span><span>,
        </span><span>@on_fail_step_id</span> <span>=</span> <span>0</span>, <span>@retry_attempts</span> <span>=</span> <span>0</span>, <span>@retry_interval</span> <span>=</span> <span>0</span><span>,
        </span><span>@os_run_priority</span> <span>=</span> <span>0</span>, <span>@subsystem</span> <span>=</span> N<span>'</span><span>TSQL</span><span>'</span>, <span>@command</span> <span>=</span> <span>@SQL</span><span>,
        </span><span>@database_name</span> <span>=</span> <span>@DBNAME</span>, <span>@flags</span> <span>=</span> <span>0</span>

<span>END</span>

  


<span>--</span><span>创建Monitor作业的调度计划</span>
<span>DECLARE</span> <span>@job_name</span><span> SYSNAME
</span><span>DECLARE</span> <span>@SQL</span> <span>NVARCHAR</span>(<span>MAX</span><span>)
</span><span>DECLARE</span> <span>@DBName</span> <span>NVARCHAR</span>(<span>MAX</span><span>)

</span><span>SET</span> <span>@DBName</span><span>=</span><span>'</span><span>xxxx</span><span>'</span>  <span>--</span><span>★Do</span>
<span>SET</span> <span>@job_name</span><span>=</span><span>'</span><span>Monitor_ActiveCursors_</span><span>'</span> <span>+</span> <span>@DBName</span>  <span>--</span><span>★Do</span>

<span>--</span><span>修改作业的执行时间</span>
<span>EXEC</span>  msdb.dbo.sp_add_jobschedule  <span>@job_name</span> <span>=</span> <span>@job_name</span>, <span>@name</span><span>=</span>N<span>'</span><span>Plan</span><span>'</span><span>, 
        </span><span>@enabled</span><span>=</span><span>1</span><span>, 
        </span><span>@freq_type</span><span>=</span><span>4</span><span>, 
        </span><span>@freq_interval</span><span>=</span><span>1</span><span>, 
        </span><span>@freq_subday_type</span><span>=</span><span>2</span><span>, 
        </span><span>@freq_subday_interval</span><span>=</span><span>30</span><span>, 
        </span><span>@freq_relative_interval</span><span>=</span><span>0</span><span>, 
        </span><span>@freq_recurrence_factor</span><span>=</span><span>0</span><span>, 
        </span><span>@active_start_date</span><span>=</span><span>20140105</span><span>, 
        </span><span>@active_end_date</span><span>=</span><span>99991231</span><span>, 
        </span><span>@active_start_time</span><span>=</span><span>2000</span><span>, 
        </span><span>@active_end_time</span><span>=</span><span>235959</span>

<span>EXEC</span>  msdb.dbo.sp_add_jobserver  <span>@job_name</span> <span>=</span> <span>@job_name</span>, <span>@server_name</span> <span>=</span> N<span>'</span><span>(local)</span><span>'</span>
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View Code

上面视图里的[object_name]字段和 [instance_name]字段跟你的环境会不一样，所以大家要按照自己的环境来修改

如果是SQLSERVER2005是没有CPU usage %这个counter的，我使用了下面的SQL语句

<span>SELECT</span> <span>SUM</span>(<span>[</span><span>cpu</span><span>]</span>) <span>FROM</span> sys.<span>[</span><span>sysprocesses</span><span>]</span> <span>WHERE</span> SPID<span>>=</span><span>50</span>
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7、画折线图

监控了一天的时间，根据结果使用EXCEL画出折线图

 记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

记一次数据库调优过程（IIS发过来SQLSERVER 的FETCH API

 

凌晨那段曲线是因为数据库有做清除数据的操作，所以会比较高

游标跟CPU图虽然说不能完全吻合，但是基本能吻合

 

解决方法

1、修改代码

2、升级到SQL2008，然后使用资源调控器把CPU压下去

 

最终还是找人修改代码

总结

有时候对一些老旧的程序，例如ASP，可能老一代程序员还会，现在的程序员基本都使用ASP.NET

所以如果可能，还是跟上技术的脚步，不然出问题了，没有人维护就麻烦了

 

如有不对的地方，欢迎大家拍砖o(∩_∩)o 

相關標籤：
iis sqlserver 資料庫 調優 過程
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