mysql報錯Changed limits: max_open_files: 5000

mysql報錯Changed limits: max_open_files: 5000

 

分類： MySQL

2018-04-08 20:39:02

 

OS:CentOS 7.4
DB:mysql 5.7.17
error.log日誌裏報錯信息：
 

1. 2018-04-08T09:52:52.641263Z 0 [Warning] Changed limits: max_open_files: 5000 (requested 50000)
2. 2018-04-08T09:52:52.641467Z 0 [Warning] Changed limits: max_connections: 4190 (requested 10000)
3. 2018-04-08T09:52:52.641476Z 0 [Warning] Changed limits: table_open_cache: 400 (requested 2000)

看到這個錯誤第一反應是去數據庫查查當前的參數都是多少，和日誌裏提示的是同樣的
 

1. mysql> show variables like '%files%';
2. +---------------------------+--------+
3. | Variable_name | Value |
4. +---------------------------+--------+
5. | character_set_filesystem | binary |
6. | innodb_log_files_in_group | 2 |
7. | innodb_open_files | 400 |
8. | keep_files_on_create | OFF |
9. | large_files_support | ON |
10. | open_files_limit | 5000 |
11. +---------------------------+--------+
12. 6 rows in set (0.00 sec)
13.  
14. mysql> show variables like '%connections%';
15. +----------------------+-------+
16. | Variable_name | Value |
17. +----------------------+-------+
18. | max_connections | 4190 |
19. | max_user_connections | 0 |
20. +----------------------+-------+
21. 2 rows in set (0.00 sec)
22.  
23.  
24. mysql> show variables like '%table_open_cache%';
25. +----------------------------+-------+
26. | Variable_name | Value |
27. +----------------------------+-------+
28. | table_open_cache | 400 |
29. | table_open_cache_instances | 16 |
30. +----------------------------+-------+
31. 2 rows in set (0.01 sec)

看到是max_open_files，難道是操做系統限制了？也沒有啊
 

1. [root@iz2ze6jo3o3bqbcongnypoz mysql]# ulimit -n
2. 65535

my.cnf文件裏也沒有對這些參數作修改，由於是用mysqld.service啓動的，難道是這個文件的問題嗎？
 

1. [root@iz2ze6jo3o3bqbcongnypoz system]# more /usr/lib/systemd/system/mysqld.service 
2. # Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
3. #
4. # This program is free software; you can redistribute it and/or modify
5. # it under the terms of the GNU General Public License as published by
6. # the Free Software Foundation; version 2 of the License.
7. #
8. # This program is distributed in the hope that it will be useful,
9. # but WITHOUT ANY WARRANTY; without even the implied warranty of
10. # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11. # GNU General Public License for more details.
12. #
13. # You should have received a copy of the GNU General Public License
14. # along with this program; if not, write to the Free Software
15. # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
16. #
17. # systemd service file for MySQL forking server
18. #
19.  
20. [Unit]
21. Description=MySQL Server
22. Documentation=man:mysqld(8)
23. Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
24. After=network.target
25. After=syslog.target
26.  
27. [Install]
28. WantedBy=multi-user.target
29.  
30. [Service]
31. User=mysql
32. Group=mysql
33.  
34. Type=forking
35.  
36. PIDFile=/var/run/mysqld/mysqld.pid
37.  
38. # Disable service start and stop timeout logic of systemd for mysqld service.
39. TimeoutSec=0
40.  
41. # Execute pre and post scripts as root
42. PermissionsStartOnly=true
43.  
44. # Needed to create system tables
45. ExecStartPre=/usr/bin/mysqld_pre_systemd
46.  
47. # Start main service
48. ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS
49.  
50. # Use this to switch malloc implementation
51. EnvironmentFile=-/etc/sysconfig/mysql
52.  
53. # Sets open_files_limit
54. LimitNOFILE = 5000

果真是...把這個參數修改成65535後，重啓mysql，問題消失了。

 

1. LimitNOFILE = 5000 這個值默認就是5000，下面這篇文檔說清楚這個事了：

https://dev.mysql.com/doc/refman/5.7/en/using-systemd.html