Problem Description:
In the Linux system high concurrency squid server, TCP time_wait socket number often reached 20,000 or 30,000, the server is easily towed to death.
Workaround:
By modifying the Linux kernel parameters, you can reduce the number of ime_wait sockets on the Linux server.
Vi/etc/sysctl.conf
Add the following lines:
Copy Code code as follows:
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
Description:
Net.ipv4.tcp_syncookies = 1 means to open syn Cookies. When the SYN wait queue overflow occurs, cookies are enabled to handle, to prevent a small number of SYN attacks, the default is 0, indicating shutdown;
Net.ipv4.tcp_tw_reuse = 1 means to turn on reuse. Allows time-wait sockets to be re used for a new TCP connection, which defaults to 0, indicating shutdown;
Net.ipv4.tcp_tw_recycle = 1 is a quick recycle of time-wait sockets on a TCP connection, and the default is 0, which means shutdown.
Net.ipv4.tcp_fin_timeout = 30 indicates that if the socket is closed by the local end, this parameter determines how long it remains in the fin-wait-2 state.
Net.ipv4.tcp_keepalive_time = 1200 means the frequency at which TCP sends keepalive messages when KeepAlive is enabled. The default is 2 hours, and 20 minutes instead.
Net.ipv4.ip_local_port_range = 1024 65000 indicates the range of ports used for outward joins. 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 for connections.
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 the warning message is printed. The default is 180000, and 5000 is changed. For Apache, Nginx and other servers, the parameters on a few lines can well reduce the number of time_wait sockets, but for squid, the effect is not. This parameter controls the maximum number of time_wait sockets and avoids the squid server being dragged to death by a large number of time_wait sockets.
Perform the following command to make the configuration effective:
/sbin/sysctl-p
