setup.sh

sysctl -w fs.file-max=12000500
sysctl -w fs.nr_open=20000500
ulimit -n 4000000
sysctl -w net.ipv4.tcp_mem='10000000 10000000 10000000'
sysctl -w net.ipv4.tcp_rmem='1024 4096 16384'
sysctl -w net.ipv4.tcp_wmem='1024 4096 16384'
sysctl -w net.core.rmem_max=16384
sysctl -w net.core.wmem_max=16384
wget http://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb
sudo dpkg -i erlang-solutions_1.0_all.deb
yes | sudo apt-get update
yes | sudo apt-get install elixir esl-erlang build-essential git gnuplot libtemplate-perl
wget http://tsung.erlang-projects.org/dist/tsung-1.6.0.tar.gz
tar -xvf tsung-1.6.0.tar.gz
cd tsung-1.6.0/
./configure
make
sudo make install
cd ..
wget https://gist.githubusercontent.com/Gazler/53b842764f778fe57757/raw/9509c3d980f13bbb739f4ae117dc84ef1d721076/phoenix.xml
git clone -b bench https://github.com/Gazler/phoenix_chat_example.git
echo "root soft nofile 4000000" >> /etc/security/limits.conf
echo "root hard nofile 4000000" >> /etc/security/limits.conf

Find out the number of connected sockets:

lsof -n -p <pid> | wc -l

Find out the ulimit of a process:

cat /proc/<pid>/limits

Using number 4000000 in /etc/security/limits.conf on Debian 9 is not working. I had to use some smaller number. Otherwise it will be using default value 1024.