MySQL 如何找出佔用CPU較高的SQL
阿新 • • 發佈：2021-12-22
在5.7版本中，MySQL通過擴充套件PERFORMANCE_SCHEMA實現了自己的實現。在THREADS表中添加了一個名為THREAD_OS_ID的新列，這是Percona Server for MySQL所採用的代替它自己的列，因為它通常保持儘可能接近上游。
The command is pidstat -t -p <mysqld_pid> 1
shell> pidstat -t -p 31258 1 03:31:06 PM UID TGID TID %usr %system %guest %CPU CPU Command [...]03:31:07 PM 10014 - 32039 5.00 1.00 0.00 6.00 22 |__mysqld 03:31:07 PM 10014 - 32040 5.00 1.00 0.00 6.00 23 |__mysqld 03:31:07 PM 10014 - 32042 6.00 1.00 0.00 7.00 8 |__mysqld 03:31:07 PM 10014 - 32047 5.00 1.00 0.00 6.00 6 |__mysqld 03:31:07 PM 10014- 32048 5.00 1.00 0.00 6.00 15 |__mysqld 03:31:07 PM 10014 - 32049 5.00 1.00 0.00 6.00 14 |__mysqld 03:31:07 PM 10014 - 32052 5.00 1.00 0.00 6.00 14 |__mysqld 03:31:07 PM 10014 - 32053 94.00 0.00 0.00 94.00 9 |__mysqld 03:31:07 PM 10014 - 320554.00 1.00 0.00 5.00 10 |__mysqld 03:31:07 PM 10014 - 4275 5.00 1.00 0.00 6.00 10 |__mysqld 03:31:07 PM 10014 - 4276 5.00 1.00 0.00 6.00 7 |__mysqld 03:31:07 PM 10014 - 4277 6.00 1.00 0.00 7.00 15 |__mysqld 03:31:07 PM 10014 - 4278 5.00 1.00 0.00 6.00 18 |__mysqld 03:31:07 PM 10014 - 4279 5.00 1.00 0.00 6.00 10 |__mysqld 03:31:07 PM 10014 - 4280 5.00 1.00 0.00 6.00 12 |__mysqld 03:31:07 PM 10014 - 4281 5.00 1.00 0.00 6.00 11 |__mysqld 03:31:07 PM 10014 - 4282 4.00 1.00 0.00 5.00 2 |__mysqld 03:31:07 PM 10014 - 35261 0.00 0.00 0.00 0.00 4 |__mysqld 03:31:07 PM 10014 - 36153 0.00 0.00 0.00 0.00 5 |__mysqld
檢視performance_schema.threads表
mysql > select * from performance_schema.threads where THREAD_OS_ID = 32053 \G *************************** 1. row *************************** THREAD_ID: 686 NAME: thread/sql/one_connection TYPE: FOREGROUND PROCESSLIST_ID: 590 PROCESSLIST_USER: msandbox PROCESSLIST_HOST: localhost PROCESSLIST_DB: NULL PROCESSLIST_COMMAND: Query PROCESSLIST_TIME: 0 PROCESSLIST_STATE: Sending data PROCESSLIST_INFO: select * from test.joinit where b = 'a a eveniet ut.' PARENT_THREAD_ID: NULL ROLE: NULL INSTRUMENTED: YES HISTORY: YES CONNECTION_TYPE: SSL/TLS THREAD_OS_ID: 32053 1 row in set (0.00 sec)
通過explain檢視執行計劃並優化
mysql > explain select * from test.joinit where b = 'a a eveniet ut.' \G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: joinit partitions: NULL type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 7170836 filtered: 10.00 Extra: Using where 1 row in set, 1 warning (0.00 sec)
https://www.percona.com/blog/2020/04/23/a-simple-approach-to-troubleshooting-high-cpu-in-mysql/