Increase ulimit

Linux

1.
# vim /etc/sysctl.conf
fs.file-max = 999999
net.ipv4.tcp_rmem = 4096 4096 16777216
net.ipv4.tcp_wmem = 4096 4096 16777216
net.ipv4.ip_local_port_range = 1024 65535

2.
# vim /etc/security/limits.conf
root	- nofile 999999
root soft nofile 999999
root hard nofile 999999
#(on a regular linux: *	- nofile 999999)

3. 
# vim /etc/pam.d/common-session
session required pam_limits.so

Reboot & Verify your settings:
# sysctl -p && cat /proc/sys/fs/file-max && ulimit -n

Consider increasing the following:
net.ipv4.tcp_max_syn_backlog
net.core.somaxconn

And decreasing 'vm.swappiness' to 5

Linux - echos

echo "fs.file-max = 999999" >> /etc/sysctl.conf
echo "net.ipv4.tcp_rmem = 4096 4096 16777216" >> /etc/sysctl.conf
echo "net.ipv4.tcp_wmem = 4096 4096 16777216" >> /etc/sysctl.conf
echo "net.ipv4.ip_local_port_range = 1024 65535" >> /etc/sysctl.conf
echo "net.ipv4.tcp_fin_timeout = 15" >> /etc/sysctl.conf
echo "root - nofile 999999" >> /etc/security/limits.conf
echo "root soft nofile 999999" >> /etc/security/limits.conf
echo "root hard nofile 999999" >> /etc/security/limits.conf
echo "session required pam_limits.so" >> /etc/pam.d/common-session

Mac OSx

1. launchctl limit maxfiles 999999 999999
2. Restart you Mac

More here:
http://research.cs.wisc.edu/condor/condorg/linux_scalability.html
http://urbanairship.com/blog/2010/09/29/linux-kernel-tuning-for-c500k/
http://wwwx.cs.unc.edu/~sparkst/howto/network_tuning.php
http://sys-notes.com/bin/view/Main/LinuxKernelOomKiller

https://gist.github.com/girvan/a341513654ad6b1cbb7f365b9f68fa7b