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mysql报错Changed limits: max_open_files: 5000

原创 作者:甲骨文技术支持 时间:2018-04-08 20:39:02 0 删除 编辑
OS:CentOS 7.4
DB:mysql 5.7.17
error.log日志里报错信息:

  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)
看到这个错误第一反应是去数据库查查当前的参数都是多少,和日志里提示的是一样的

  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. mysql> show variables like '%connections%';
  14. +----------------------+-------+
  15. | Variable_name | Value |
  16. +----------------------+-------+
  17. | max_connections | 4190 |
  18. | max_user_connections | 0 |
  19. +----------------------+-------+
  20. 2 rows in set (0.00 sec)


  21. mysql> show variables like '%table_open_cache%';
  22. +----------------------------+-------+
  23. | Variable_name | Value |
  24. +----------------------------+-------+
  25. | table_open_cache | 400 |
  26. | table_open_cache_instances | 16 |
  27. +----------------------------+-------+
  28. 2 rows in set (0.01 sec)

看到是max_open_files,难道是操作系统限制了?也没有啊

  1. [root@iz2ze6jo3o3bqbcongnypoz mysql]# ulimit -n
  2. 65535
my.cnf文件里也没有对这些参数做修改,因为是用mysqld.service启动的,难道是这个文件的问题吗?

  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. [Unit]
  20. Description=MySQL Server
  21. Documentation=man:mysqld(8)
  22. Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
  23. After=network.target
  24. After=syslog.target

  25. [Install]
  26. WantedBy=multi-user.target

  27. [Service]
  28. User=mysql
  29. Group=mysql

  30. Type=forking

  31. PIDFile=/var/run/mysqld/mysqld.pid

  32. # Disable service start and stop timeout logic of systemd for mysqld service.
  33. TimeoutSec=0

  34. # Execute pre and post scripts as root
  35. PermissionsStartOnly=true

  36. # Needed to create system tables
  37. ExecStartPre=/usr/bin/mysqld_pre_systemd

  38. # Start main service
  39. ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS

  40. # Use this to switch malloc implementation
  41. EnvironmentFile=-/etc/sysconfig/mysql

  42. # Sets open_files_limit
  43. LimitNOFILE = 5000

果然是...把这个参数修改为65535后,重启mysql,问题消失了。


  1. LimitNOFILE = 5000 这个值默认就是5000,下面这篇文档说清楚这个事了:

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



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