Vertical Superscale

Clear *nix Socket Descriptors Faster

In Linux, TCP keepalive parameters are:
 
tcp_keepalive_intvl
tcp_keepalive_probes
tcp_keepalive_time

Their default values are:
 
tcp_keepalive_time = 7200 (seconds)
tcp_keepalive_intvl = 75 (seconds)
tcp_keepalive_probes = 9 (number of probes)


For example, to reduce the value of /proc/sys/net/ipv4/tcp_keepalive_time from 7,200 (2 hours) 
to 300 (5 Min) we can use  the command: 

echo 300 > /proc/sys/net/ipv4/tcp_keepalive_time
OR
sysctl -w net.ipv4.tcp_keepalive_time=300

Both of these are temporary methods. To permanently change to TCP Keepalive add the following 
to the /etc/sysctl.conf file - 

net.ipv4.tcp_keepalive_time=300 

NOTE: All the above commands require root user access to run.

system config

Increase socket descriptors limit - 
ulimit -n 18000000

Increase kernel socket descriptors limit - 
echo 18000000 > /proc/sys/fs/nr_open

test client system config

Configure available ephemeral ports - 
sysctl -w net.ipv4.ip_local_port_range="500   65535"