How to optimize Nginx high concurrency kernel

What is high concurrency

• The default Linux kernel parameters consider the most common scenarios and are not suitable for web applications that support high concurrent access. server, so you need to modify the Linux kernel parameters, so that nginx can have higher performance; To make adjustments, when nginx is used as a static web content server, a reverse proxy, or a server that provides a compression server, the adjustments to the kernel parameters are different. Here are the most common TCP network parameters that enable nginx to support more concurrent requests. Make simple configurations;

• These require modifying /etc/sysctl.conf to change the kernel parameters.

• Configuration method

Configuration detailed analysis

#Indicates that a single process is large The number of handles that can be opened; the

fs.file-max = 999999

# parameter is set to 1, which means that the socket in the time_wait state is allowed to be reused for a new tcp link. This is of great significance to the server because there are always a large number of links in the time_wait state. Exists;

net.ipv4.tcp_tw_reuse = 1

#When keepalive is started, the frequency of tcp sending keepalive messages; the default is 2 hours, setting it to 10 minutes can clean up invalid links faster.

ner.ipv4.tcp_keepalive_time = 600

#When the server actively closes the link, the maximum time the socket remains in the fin_wait_2 state

net.ipv4.tcp_fin_timeout = 30

#This parameter indicates the maximum value of the number of time_wait sockets allowed by the operating system. If it exceeds With this number, the time_wait socket will be cleared immediately and a warning message will be printed.

#This parameter defaults to 180000. Too many time_wait sockets will slow down the web server.

net.ipv4.tcp_max_tw_buckets = 5000

#Define the value range of the local port for udp and tcp links.

net.ipv4.ip_local_port_range = 1024 65000

# Defines the minimum value, default value, and maximum value for tcp to accept cache.

net.ipv4.tcp_rmem = 10240 87380 12582912

#Define the minimum value, default value and maximum value of tcp send cache.

net.ipv4.tcp_wmem = 10240 87380 12582912

#When the network card receives data packets faster than the kernel processing speed, there will be a queue to save these data packets. This parameter represents the maximum value of the queue.

net.core.netdev_max_backlog = 8096

#Indicates that the kernel socket accepts the default size of the buffer area.

net.core.rmem_default = 6291456

# indicates the default size of the kernel socket send buffer.

net.core.wmem_default = 6291456

#Indicates that the kernel socket accepts a larger buffer size.

net.core.rmem_max = 12582912

#Indicates the larger size of the kernel socket send buffer.

net.core.wmem_max = 12582912

Note: The above four configurations need to be comprehensively considered based on business logic and actual hardware costs;

# has nothing to do with performance. Used to solve tcp syn***.

net.ipv4.tcp_syncookies = 1

#This parameter indicates the maximum length of the syn request queue accepted during the TCP three-way handshake establishment phase. The default is 1024. Setting it larger can prevent Linux from being too busy to accept new connections when nginx is busy. Lost client-initiated link request.

net.ipv4.tcp_max_syn_backlog = 8192

#This parameter is used to set and enable timewait fast recycling.

net.ipv4.tcp_tw_recycle = 1

The default value of the option is 128. This parameter is used to adjust the number of TCP connections initiated by the system at the same time. In high-concurrency requests, the default value may cause the link to time out or retransmit, so it needs to be combined with high concurrency. Adjust this value based on the number of requests. The

net.core.somaxconn=262114

# option is used to set the maximum number of tcp sockets in the system that are not associated with any user file handle. If this number is exceeded, the orphan link will be reset immediately and a warning message will be output. This limit indicates that in order to prevent simple dos***, you do not need to rely too much on this limit or even reduce this value. In more cases, increase this value.

net.ipv4.tcp_max_orphans=262114

For ease of use, you can copy it directly below

net.ipv4.tcp_tw_reuse = 1
fs.file-max = 999999
net.ipv4.tcp_fin_timeout = 30
ner.ipv4.tcp_keepalive_time = 600

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