How do I increase the maximum number of open files under CentOS Linux? How do I open more file descriptors under Linux?
The ulimit command provides control over the resources available to the shell and/or to processes started by it, on systems that allow such control. The maximum number of open file descriptors displayed with following command (login as the root user).
ulimit 命令提供了针对 shell 和/或由该 shell 启动的进程占用资源的控制。
Command To List Number Of Open File Descriptors
Use the following command to display maximum number of open file descriptors:
|
1 |
|
Output:
|
1 |
|
75000 files normal user can have open in single login session . To see the hard and soft values, issue the command as follows:
|
1 2 |
|
To see the hard and soft values for httpd or oracle user, issue the command as follows:
通过切换登陆用户，可以查看针对特定登陆用户所设置的 fd 限制数目。
|
1 |
|
In this example, su to oracle user, enter:
|
1 2 3 |
|
System-wide File Descriptors (FD) Limits
The number of concurrently open file descriptors throughout the system can be changed via /etc/sysctl.conf file under Linux operating systems.
系统范围级别的 fd 数量控制需要编辑 /etc/sysctl.conf 内核参数配置文件。
The Number Of Maximum Files Was Reached, How Do I Fix This Problem?
Many application such as Oracle database or Apache web server needs this range quite higher. So you can increase the maximum number of open files by setting a new value in kernel variable /proc/sys/fs/file-max as follows (login as the root):
通过调整内核参数 /proc/sys/fs/file-max 来增加可打开 fd 数目。
|
1 |
|
Above command forces the limit to 100000 files. You need to edit /etc/sysctl.conf file and put following line so that after reboot the setting will remain as it is:
通过修改 /etc/sysctl.conf 文件，可以在令针对 fd 的修改一直生效。
|
1 |
|
Append a config directive as follows:
|
1 |
|
Save and close the file. Users need to log out and log back in again to changes take effect or just type the following command:
|
1 |
|
Verify your settings with command:
|
1 |
|
OR
|
1 |
|
User Level FD Limits
The above procedure sets system-wide file descriptors (FD) limits. However, you can limit httpd (or any other users) user to specific limits by editing /etc/security/limits.conf file, enter:
通过修改 /etc/security/limits.conf 文件可以在用户级别对 fd 进行限制。
|
1 |
|
Set httpd user soft and hard limits as follows:
|
1 2 |
|
Save and close the file. To see limits, enter:
|
1 2 3 |
|