How to configure the maximum number of connections in Nginx

Configuring the maximum number of Nginx worker processes

##worker_processes: The maximum number of worker processes

##work_connections: Each worker process The number of external connections that can be allowed to be established simultaneously.

Modify the maximum number of files that can be opened

Change the setting of the "maximum number of files that can be opened by a process" of the operating system

First, you need root permissions of the operating system , then you need the limits.conf main configuration file:

[root@localhost /]# vim /etc/security/limits.conf

Add the following statements to the file

* soft nofile 65535
* hard nofile 65535

Note: * To add to the file, the above two sentences added to the limits.conf file The meaning is

soft (application software) level limit on the maximum number of open files.
hard means the operating system level limit on the maximum number of open files.
* means it is valid for all users.

It will not take effect immediately after saving the file. You need to use the following command

ulimit -n 65535

Use ulimit -a to view

[root@localhost /]# ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 14989
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 65535
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 14989
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

open files has become 65535

Change Nginx "Maximum number of open files for a process" Settings

Open nginx.conf and match the worker_rlimit_nofile attribute.

#user  nobody;
worker_processes  4;
#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;
#pid        logs/nginx.pid;
events {
    use epoll;
    worker_connections  65535;
}

Verify whether Nginx's "maximum number of open files for a process" works

In Linux, all processes will have a temporary core configuration file description and storage path In /proc/process number/limit

[root@localhost sbin]# ps -aux|grep nginx
root       1733  0.0  0.0  32816  1792 ?        Ss   17:38   0:00 nginx: master process ./nginx
nobody     1734  0.0  0.7  59952 29184 ?        S    17:38   0:00 nginx: worker process
nobody     1735  0.1  0.7  59952 29184 ?        S    17:38   0:00 nginx: worker process
nobody     1736  0.2  0.7  59952 29184 ?        S    17:38   0:00 nginx: worker process
nobody     1737  0.1  0.7  59952 28928 ?        S    17:38   0:00 nginx: worker process
root       1739  0.0  0.0 112824   980 pts/0    S+   17:38   0:00 grep --color=auto nginx
[root@localhost sbin]# cat /proc/1734/limits
Limit                     Soft Limit           Hard Limit           Units     
Max cpu time              unlimited            unlimited            seconds   
Max file size             unlimited            unlimited            bytes     
Max data size             unlimited            unlimited            bytes     
Max stack size            8388608              unlimited            bytes     
Max core file size        0                    unlimited            bytes     
Max resident set          unlimited            unlimited            bytes     
Max processes             14989                14989                processes 
Max open files            65535                65535                files     
Max locked memory         65536                65536                bytes     
Max address space         unlimited            unlimited            bytes     
Max file locks            unlimited            unlimited            locks     
Max pending signals       14989                14989                signals   
Max msgqueue size         819200               819200               bytes     
Max nice priority         0                    0                    
Max realtime priority     0                    0                    
Max realtime timeout      unlimited            unlimited            us

The Soft Limit and Hard Limit of Max open files have been set to 65535

Max client calculation method

#充当服务器时Nginx可同时承载的连接数量，是最大工作线程*每个线程允许的连接数量
max_client = worker_processes * worker_connections
#充当反向代理服务时，可同时承载的连接数量是最大工作线程*每个线程允许的连接数量/4
#（4）代表：浏览器会建立两条连接到Nginx，Nginx也会建立两条连接到后端服务器。这样就是4条了。
max_client = worker_processes * worker_connections/4

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