如何找出Mysql中CPU占用高的查询

查看具体查是哪个线程占用CPU最高

# 在Linux中使用top命令找到mysql进程ID
top - 22:11:02 up 279 days,  3:05,  0 users,  load average: 5.01, 6.78, 6.42
Tasks:   3 total,   1 running,   2 sleeping,   0 stopped,   0 zombie
%Cpu(s): 76.4 us,  6.8 sy,  0.0 ni, 13.3 id,  1.5 wa,  0.0 hi,  2.0 si,  0.0 st
MiB Mem :   7821.6 total,    133.8 free,   3278.6 used,   4409.2 buff/cache
MiB Swap:   2048.0 total,    393.7 free,   1654.3 used.   4243.3 avail Mem 

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                                                                                                   
    1 mysql     20   0 5850828   2.8g   9560 S 676.7  36.9 218111:07 mysqld                                                                                                    
29839 root      20   0    5740   2044   1580 S   0.0   0.0   0:00.01 bash                                                                                                      
29845 root      20   0    9816   1848   1388 R   0.0   0.0   0:00.00 top         
# 指定进程ID，找到占用CPU最高的线程ID
top -H -p 1
top - 22:11:36 up 279 days,  3:05,  0 users,  load average: 5.41, 6.70, 6.41
Threads: 1102 total,   4 running, 1098 sleeping,   0 stopped,   0 zombie
%Cpu(s): 39.3 us,  2.3 sy,  0.0 ni, 56.2 id,  1.7 wa,  0.0 hi,  0.4 si,  0.0 st
MiB Mem :   7821.6 total,    126.3 free,   3272.0 used,   4423.3 buff/cache
MiB Swap:   2048.0 total,    392.4 free,   1655.6 used.   4250.5 avail Mem 

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                                                                                                   
17943 mysql     20   0 5847756   2.8g   9560 R  81.5  36.8  12:02.04 mysqld                                                                                                    
10532 mysql     20   0 5847756   2.8g   9560 R  58.7  36.8   9:18.74 mysqld                                                                                                    
31587 mysql     20   0 5847756   2.8g   9560 S  30.7  36.8  52:08.27 mysqld                                                                                                    
14865 mysql     20   0 5847756   2.8g   9560 R  27.7  36.8  37:45.00 mysqld                                                                                                    
22558 mysql     20   0 5847756   2.8g   9560 S  21.1  36.8  22:24.18 mysqld                                                                                                    
 6064 mysql     20   0 5847756   2.8g   9560 S  16.8  36.8   4:01.18 mysqld  

根据操作系统线程ID找到对应的mysql 线程ID

SELECT
    * 
FROM
    `performance_schema`.threads T 
WHERE
    T.THREAD_OS_ID = 17943

根据返回结果中的PROCESLIST_INFO等信息，来判断其执行的语句是否可以进行优化

SELECT * FROM `performance_schema`.`processlist` WHERE `processlist`.ID IN
(SELECT
    T.PROCESSLIST_ID
FROM
    `performance_schema`.threads T 
WHERE
    T.THREAD_OS_ID = 7013)

注意：docker运行的mysql要在容器内找到线程ID

# 如果容易内没有top命令，如果昌官方基于 debian的mysql镜像，使用如下命令安装top命令
apt-get update
apt-get install procps
# 必须执行apt-get update，否则可能会报E: Unable to locate package procps的错

补充

如果觉得先从分析线程入手比较麻烦，也可以直接通过查询当前正在执行的查询入手

SELECT * FROM `performance_schema`.`processlist` 
WHERE COMMAND != 'SLEEP' AND TIME > 1 ORDER BY TIME DESC

直接找出当前下大执行的查询，按执行时间倒充值，占用CPU高的查询往往耗时也比较长

参考文章列表

Mysql thread 与 OS thread
mysql show processlist排查问题