MySQL性能瓶颈分析工具（profiling）

时间  2019-11-11
标签 mysql 性能 瓶颈 分析 工具 profiling 栏目 MySQL 繁體版
原文   原文链接

1、介绍
一、分析SQL执行带来的开销是优化SQL的重要手段。
二、在MySQL数据库中，能够经过配置profiling参数来启用SQL剖析。
三、该参数能够在全局和session级别来设置。
四、对于全局级别则做用于整个MySQL实例，而session级别紧影响当前session。
五、该参数开启后，后续执行的SQL语句都将记录其资源开销，诸如IO，上下文切换，CPU，Memory等等。根据这些开销进一步分析当前SQL瓶颈从而进行优化与调整。
2、有关profile的描述
show variables like 'version';
版本介绍
show variables like '%profil%';
查看profiling系统变量mysql

mysql> show variables like '%profil%';  
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| have_profiling         | YES   |          --只读变量，用于控制是否由系统变量开启或禁用profiling
| profiling              | OFF   |               --开启SQL语句剖析功能
| profiling_history_size | 15    |          --设置保留profiling的数目，缺省为15，范围为0至100，为0时将禁
+------------------------+-------+
3 rows in set (0.00 sec)

--获取profile的帮助
root@localhost[sakila]> help profile;
Name: 'SHOW PROFILE'
Description:
Syntax:
SHOW PROFILE [type [, type] ... ]
[FOR QUERY n]
[LIMIT row_count [OFFSET offset]] sql

type:
ALL --显示全部的开销信息
| BLOCK IO --显示块IO相关开销
| CONTEXT SWITCHES --上下文切换相关开销
| CPU --显示CPU相关开销信息
| IPC --显示发送和接收相关开销信息
| MEMORY --显示内存相关开销信息
| PAGE FAULTS --显示页面错误相关开销信息
| SOURCE --显示和Source_function，Source_file，Source_line相关的开销信息
| SWAPS --显示交换次数相关开销的信息 数据库

二、开启porfiling
--启用session级别的profiling  
root@localhost[sakila]> set profiling=1;  
Query OK, 0 rows affected, 1 warning (0.00 sec)  

--验证修改后的结果  
root@localhost[sakila]> show variables like '%profil%';  
+------------------------+-------+  
| Variable_name          | Value |  
+------------------------+-------+  
| have_profiling         | YES   |  
| profiling              | ON    |  
| profiling_history_size | 15    |  
+------------------------+-------+  

--发布SQL查询  
root@localhost[sakila]> select count(*) from customer;  
+----------+  
| count(*) |  
+----------+  
|      599 |  
+----------+  

--查看当前session全部已产生的profile  
root@localhost[sakila]> show profiles;  
+----------+------------+--------------------------------+  
| Query_ID | Duration   | Query                          |  
+----------+------------+--------------------------------+  
|        1 | 0.00253600 | show variables like '%profil%' |  
|        2 | 0.00138150 | select count(*) from customer  |  
+----------+------------+--------------------------------+  
2 rows in set, 1 warning (0.01 sec)  

--咱们看到有2个warning，以前一个，如今一个  
root@localhost[sakila]> show warnings;    --下面的结果代表SHOW PROFILES未来会被Performance Schema替换掉  
+---------+------+--------------------------------------------------------------------------------------------------------------+  
| Level   | Code | Message                                                                                                      |  
+---------+------+--------------------------------------------------------------------------------------------------------------+  
| Warning | 1287 | 'SHOW PROFILES' is deprecated and will be removed in a future release. Please use Performance Schema instead |  
+---------+------+--------------------------------------------------------------------------------------------------------------+

三、获取SQL语句的开销信息session

--能够直接使用show profile来查看上一条SQL语句的开销信息  
--注，show profile之类的语句不会被profiling，即自身不会产生Profiling  
--咱们下面的这个show profile查看的是show warnings产生的相应开销  
root@localhost[sakila]> show profile;    
+----------------+----------+  
| Status         | Duration |  
+----------------+----------+  
| starting       | 0.000141 |  
| query end      | 0.000058 |  
| closing tables | 0.000014 |  
| freeing items  | 0.001802 |  
| cleaning up    | 0.000272 |  
+----------------+----------+  

--以下面的查询show warnings被添加到profiles  
root@localhost[sakila]> show profiles;  
+----------+------------+--------------------------------+  
| Query_ID | Duration   | Query                          |  
+----------+------------+--------------------------------+  
|        1 | 0.00253600 | show variables like '%profil%' |  
|        2 | 0.00138150 | select count(*) from customer  |  
|        3 | 0.00228600 | show warnings                  |  
+----------+------------+--------------------------------+  

--获取指定查询的开销  
root@localhost[sakila]> show profile for query 2;  
+----------------------+----------+  
| Status               | Duration |  
+----------------------+----------+  
| starting             | 0.000148 |  
| checking permissions | 0.000014 |  
| Opening tables       | 0.000047 |  
| init                 | 0.000023 |  
| System lock          | 0.000035 |  
| optimizing           | 0.000012 |  
| statistics           | 0.000019 |  
| preparing            | 0.000014 |  
| executing            | 0.000006 |  
| Sending data         | 0.000990 |  
| end                  | 0.000010 |  
| query end            | 0.000011 |  
| closing tables       | 0.000010 |  
| freeing items        | 0.000016 |  
| cleaning up          | 0.000029 |  
+----------------------+----------+  

--查看特定部分的开销，以下为CPU部分的开销  
root@localhost[sakila]> show profile cpu for query 2 ;  
+----------------------+----------+----------+------------+  
| Status               | Duration | CPU_user | CPU_system |  
+----------------------+----------+----------+------------+  
| starting             | 0.000148 | 0.000000 |   0.000000 |  
| checking permissions | 0.000014 | 0.000000 |   0.000000 |  
| Opening tables       | 0.000047 | 0.000000 |   0.000000 |  
| init                 | 0.000023 | 0.000000 |   0.000000 |  
| System lock          | 0.000035 | 0.000000 |   0.000000 |  
| optimizing           | 0.000012 | 0.000000 |   0.000000 |  
| statistics           | 0.000019 | 0.000000 |   0.000000 |  
| preparing            | 0.000014 | 0.000000 |   0.000000 |  
| executing            | 0.000006 | 0.000000 |   0.000000 |  
| Sending data         | 0.000990 | 0.001000 |   0.000000 |  
| end                  | 0.000010 | 0.000000 |   0.000000 |  
| query end            | 0.000011 | 0.000000 |   0.000000 |  
| closing tables       | 0.000010 | 0.000000 |   0.000000 |  
| freeing items        | 0.000016 | 0.000000 |   0.000000 |  
| cleaning up          | 0.000029 | 0.000000 |   0.000000 |  
+----------------------+----------+----------+------------+  

--以下为MEMORY部分的开销  
root@localhost[sakila]> show profile memory for query 2 ;  
+----------------------+----------+  
| Status               | Duration |  
+----------------------+----------+  
| starting             | 0.000148 |  
| checking permissions | 0.000014 |  
| Opening tables       | 0.000047 |  
| init                 | 0.000023 |  
| System lock          | 0.000035 |  
| optimizing           | 0.000012 |  
| statistics           | 0.000019 |  
| preparing            | 0.000014 |  
| executing            | 0.000006 |  
| Sending data         | 0.000990 |  
| end                  | 0.000010 |  
| query end            | 0.000011 |  
| closing tables       | 0.000010 |  
| freeing items        | 0.000016 |  
| cleaning up          | 0.000029 |  
+----------------------+----------+  

--同时查看不一样资源开销  
root@localhost[sakila]> show profile block io,cpu for query 2;  
+----------------------+----------+----------+------------+--------------+---------------+  
| Status               | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |  
+----------------------+----------+----------+------------+--------------+---------------+  
| starting             | 0.000148 | 0.000000 |   0.000000 |            0 |             0 |  
| checking permissions | 0.000014 | 0.000000 |   0.000000 |            0 |             0 |  
| Opening tables       | 0.000047 | 0.000000 |   0.000000 |            0 |             0 |  
| init                 | 0.000023 | 0.000000 |   0.000000 |            0 |             0 |  
| System lock          | 0.000035 | 0.000000 |   0.000000 |            0 |             0 |  
| optimizing           | 0.000012 | 0.000000 |   0.000000 |            0 |             0 |  
| statistics           | 0.000019 | 0.000000 |   0.000000 |            0 |             0 |  
| preparing            | 0.000014 | 0.000000 |   0.000000 |            0 |             0 |  
| executing            | 0.000006 | 0.000000 |   0.000000 |            0 |             0 |  
| Sending data         | 0.000990 | 0.001000 |   0.000000 |            0 |             0 |  
| end                  | 0.000010 | 0.000000 |   0.000000 |            0 |             0 |  
| query end            | 0.000011 | 0.000000 |   0.000000 |            0 |             0 |  
| closing tables       | 0.000010 | 0.000000 |   0.000000 |            0 |             0 |  
| freeing items        | 0.000016 | 0.000000 |   0.000000 |            0 |             0 |  
| cleaning up          | 0.000029 | 0.000000 |   0.000000 |            0 |             0 |  
+----------------------+----------+----------+------------+--------------+---------------+  

--下面的SQL语句用于查询query_id为2的SQL开销，且按最大耗用时间倒序排列  
root@localhost[sakila]> set @query_id=2;  

root@localhost[sakila]> SELECT STATE, SUM(DURATION) AS Total_R,  
    ->   ROUND(  
    ->        100 * SUM(DURATION) /  
    ->           (SELECT SUM(DURATION)  
    ->            FROM INFORMATION_SCHEMA.PROFILING  
    ->            WHERE QUERY_ID = @query_id  
    ->        ), 2) AS Pct_R,  
    ->     COUNT(*) AS Calls,  
    ->     SUM(DURATION) / COUNT(*) AS "R/Call"  
    ->  FROM INFORMATION_SCHEMA.PROFILING  
    ->  WHERE QUERY_ID = @query_id  
    ->  GROUP BY STATE  
    ->  ORDER BY Total_R DESC;  
+----------------------+----------+-------+-------+--------------+  
| STATE                | Total_R  | Pct_R | Calls | R/Call       |  
+----------------------+----------+-------+-------+--------------+  
| Sending data         | 0.000990 | 71.53 |     1 | 0.0009900000 |--最大耗用时间部分为发送数据  
| starting             | 0.000148 | 10.69 |     1 | 0.0001480000 |  
| Opening tables       | 0.000047 |  3.40 |     1 | 0.0000470000 |  
| System lock          | 0.000035 |  2.53 |     1 | 0.0000350000 |  
| cleaning up          | 0.000029 |  2.10 |     1 | 0.0000290000 |  
| init                 | 0.000023 |  1.66 |     1 | 0.0000230000 |  
| statistics           | 0.000019 |  1.37 |     1 | 0.0000190000 |  
| freeing items        | 0.000016 |  1.16 |     1 | 0.0000160000 |  
| preparing            | 0.000014 |  1.01 |     1 | 0.0000140000 |  
| checking permissions | 0.000014 |  1.01 |     1 | 0.0000140000 |  
| optimizing           | 0.000012 |  0.87 |     1 | 0.0000120000 |  
| query end            | 0.000011 |  0.79 |     1 | 0.0000110000 |  
| end                  | 0.000010 |  0.72 |     1 | 0.0000100000 |  
| closing tables       | 0.000010 |  0.72 |     1 | 0.0000100000 |  
| executing            | 0.000006 |  0.43 |     1 | 0.0000060000 |  
+----------------------+----------+-------+-------+--------------+  

--开启profiling后，咱们能够经过show profile等方式查看，其实质是这些开销信息被记录到information_schema.profiling表  
--以下面的查询，部分信息省略  
profiling  
root@localhost[information_schema]> select * from profiling limit 3,3\G;  
*************************** 1. row ***************************  
           QUERY_ID: 1  
                SEQ: 5  
              STATE: init  
           DURATION: 0.000020  
           CPU_USER: 0.000000  
         CPU_SYSTEM: 0.000000  
  CONTEXT_VOLUNTARY: 0  
CONTEXT_INVOLUNTARY: 0  
       BLOCK_OPS_IN: 0  
      BLOCK_OPS_OUT: 0  
      MESSAGES_SENT: 0  
  MESSAGES_RECEIVED: 0  
  PAGE_FAULTS_MAJOR: 0  
  PAGE_FAULTS_MINOR: 0  
              SWAPS: 0  
    SOURCE_FUNCTION: mysql_prepare_select  
        SOURCE_FILE: sql_select.cc  
        SOURCE_LINE: 1050  

--中止profile,能够设置profiling参数，或者在session退出以后,profiling会被自动关闭  
root@localhost[sakila]> set profiling=off;  
Query OK, 0 rows affected, 1 warning (0.00 sec)

本文摘抄自MySQL性能分析工具profile使用教程ide

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