Nginx Tuning

Nginx Configuration

Requirement: Serve around 200 requests/second with with a system of 4 CPU core and 8 Gb of memory

Given Configuration
===============================================================
user www-data;
worker_processes 8; 
pid /var/run/nginx.pid;

 events {
        worker_connections 4096;
        multi_accept on;
}

 http {
        sendfile on;
        tcp_nopush on;
        tcp_nodelay on;
        keepalive_timeout 30;
        types_hash_max_size 2048;
        ….
        …
        ….
}
===============================================================

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## The problem with the above configuration ##
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We would have to serve an application that is mostly static. This means that we
would not have to perform much processor intensive operation. So rather than using
2 worker processes per core we should be using 1 work process per core.

	worker_processes 8 -> 4

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## Optimization ##
------------------

To further optimize the performance of the Nginx server we can make the following configuration changes

~ Increase limit of open files (so that Nginx can create greater number of connections).
  Add the below line after “worker_processes”

	worker_rlimit_nofile 65000;

~ Use Epoll so that Nginx server prioritizes the active connections.
  Add the following line inside the “events” section.
  
	use epoll;

~ Modify GZip configurations so that network performance can be improved
	gzip on;
	gzip_static on;
	gzip_proxied any;
	gzip_min_length 256;
	gzip_comp_level 4;
	gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss 	text/javascript;

~ Modify caching mechanism to decrease Disk I/O
	open_file_cache max=65000 inactive=20s;
	open_file_cache_valid 30s;
	open_file_cache_min_uses 2;
	open_file_cache_errors on;

 
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## External System Settings ##
------------------------------

~ Change the limit number of open file for Nginx system user, so that the webserver doesn’t get 
  blocked while opening connections.

	~ Configure limits.conf
		- sudo nano /etc/security/limits.conf    # open the file
		- Add the following lines at the end of the file
			www-data  soft  nofile 200000
			www-data  hard  nofile 200000

	~ Configure the common-session file
		- sudo nano  /etc/pam.d/common-session
		- Add the following line at the end of the file
			session required pam_limits.so
	
	~ Reboot the system
		- sudo reboot
	
	~ Check the changed value
		- ulimit -n

~ Change the following kernel parameters to increase the number of ephemeral ports, 
  reduce TIME_WAIT and increase the allowed listen backlog:

	~ Use the following commands to make the changes
		- echo "2048 64512" > /proc/sys/net/ipv4/ip_local_port_range
		- echo "1" > /proc/sys/net/ipv4/tcp_tw_recycle
		- echo "1" > /proc/sys/net/ipv4/tcp_tw_reuse
		- echo "10" > /proc/sys/net/ipv4/tcp_fin_timeout
		- echo "65536" > /proc/sys/net/ipv4/tcp_max_syn_backlog