Modifying the Linux kernel parameters to improve the concurrency performance of Nginx server

When the Linux nginx reaches a high number of concurrency, the number of TCP time_wait sockets often reaches 20,000 or 30,000, so the server can easily be dragged to death. In fact, we can simply modify the Linux kernel parameters, can reduce the number of time_wait sockets of Nginx server, and thus improve the performance of Nginx server concurrency.

Vi/etc/sysctl.conf

Add the following lines:
Net.ipv4.tcp_fin_timeout = 30
Net.ipv4.tcp_keepalive_time = 1200

Net.ipv4.tcp_syncookies = 1
Net.ipv4.tcp_tw_reuse = 1
Net.ipv4.tcp_tw_recycle = 1
Net.ipv4.ip_local_port_range = 1024 65000
Net.ipv4.tcp_max_syn_backlog = 8192
Net.ipv4.tcp_max_tw_buckets = 5000 Simple Description:
Net.ipv4.tcp_syncookies = 1 means that Syn Cookies are turned on. When there is a SYN wait queue overflow, cookies are enabled to protect against a small number of SYN attacks, the default is 0, which means close;
Net.ipv4.tcp_tw_reuse = 1 means turn on reuse. Allows time-wait sockets to be re-used for new TCP connections, which defaults to 0, which means shutdown;
Net.ipv4.tcp_tw_recycle = 1 means a fast recycle of time-wait sockets in the TCP connection is turned on, and the default is 0, which means shutdown.
Net.ipv4.tcp_fin_timeout = 30 means that if the socket is closed by the local side, this parameter determines how long it remains in the fin-wait-2 state.
Net.ipv4.tcp_keepalive_time = 1200 indicates the frequency at which TCP sends keepalive messages when KeepAlive is employed. The default is 2 hours, which is changed to 20 minutes.
Net.ipv4.ip_local_port_range = 1024 65000 indicates the range of ports used for an outward connection. Small by default: 32768 to 61000, 1024 to 65000.
Net.ipv4.tcp_max_syn_backlog = 8192 Indicates the length of the SYN queue, the default is 1024, and the queue length is 8192, which can accommodate more network connections waiting to be connected.
Net.ipv4.tcp_max_tw_buckets = 5000 indicates that the system maintains the maximum number of time_wait sockets at the same time, and if this number is exceeded, the time_wait socket is immediately cleared and a warning message is printed. The default is 180000, which changes to 5000. For Apache, Nginx and other servers, the parameters of the last few lines can be a good way to reduce the number of time_wait sockets, but for squid, the effect is not small. This parameter controls the maximum number of time_wait sockets, preventing squid servers from being dragged to death by a large number of time_wait sockets.

echo "====================== executes the following command to make the configuration effective: ========================="
#更改linux内核参数后, immediate effect of the order!

/sbin/sysctl-p

Nginx optimization

Using the FASTCGI cache
Fastcgi_cache TEST
Turn on the fastcgi cache and set a name for it. The personal sense of unlocking the cache is useful to reduce CPU load and prevent 502 errors.

Fastcgi_cache_path/usr/local/nginx/fastcgi_cache Levels=1:2
keys_zone=test:10m
inactive=5m;
This directive specifies a path for the fastcgi cache, directory structure level, key area storage time, and inactive delete time

Other instructions

Nginx was developed by Igor Sysoev, the second-most visited rambler.ru site in Russia, which has already run more than 2.5 of the site. Igor release the source code in the form of a BSD-like license.

In the case of high concurrent connection, Nginx is a good substitute for Apache server. Nginx can also be used as a 7-tier load balancer server. According to my test results, Nginx 0.6.31 + PHP 5.2.6 (FastCGI) can withstand more than 30,000 concurrent connections, equivalent to 10 times times Apache in the same environment.

In my experience, the server +apache (prefork mode) of 4GB memory typically handles only 3,000 concurrent connections because they will consume more than 3GB of memory and have to reserve 1GB of memory for the system. I used to have two Apache servers, because the maxclients set in the configuration file is 4000, when the number of Apache concurrent connections reached 3800, causing the server memory and swap space to be full and crashed.

And this nginx 0.6.31 + PHP 5.2.6 (FastCGI) server in 30,000 concurrent connection, open 10 Nginx process consumes 150M memory (15m*10=150m), open 64 php-cgi process consumes 1280M of memory (20m*64 =1280m), combined with the memory consumed by the system itself, consumes less than 2GB of memory. If the server memory is small, you can only open 25 php-cgi processes, so that the total amount of memory consumed by php-cgi is 500M.

Modifying the Linux kernel parameters to improve the concurrency performance of Nginx server