Today, I want to describe one of the interesting tools I am using in my job. This tool is nginx - small, but very powerful and efficient web server created by Igor Sysoev for large Russian web company Rambler and kindly provided by open-source community. This server can be used as standalone HTTP-server and as reverse proxy server before some Apache or another “big” server” to reduce load to backend server by many concurrent HTTP-sessions. As standalone web server, nginx can easily handle huge http-load on static files (images, html-pages, etc).

Main features of nginx server:

  • Handling requests to static content, automatical handling of index files and building directory listings.
  • Accelerated proxying without caching, simple load banancing and fail-over.
  • Accelerated support of remote FastCGI servers with simple load banancing and fail-over.
  • Modules and filters including compression (gzip), byte-ranges, chunked responses, SSI-filter, concurrently executed FastCGI or proxy subrequests from one SSI-page.
  • SSL-support.

Advanced features of nginx server:

  • IP-based and name-based virtual servers.
  • Support for keep-alive and pipelined connections.
  • Flexible configurations like in Apache, tunable timeouts and buffers.
  • Config file and even executable file updating without any termination in service.
  • Tunable log files with fast rotation.
  • Special pages for errors 400-599.
  • Very efficient URI rewriting with regular expressions.
  • Access rules based on client’s IP address and on pasword (Basic auth).
  • Download speed limits.

Main architecture specifics of nginx server:

  • One management and many worker processes; workers are running from non-privileged user.
  • Support for different techniques for asynchronous sockets handling: kqueue (FreeBSD 4.1+), epoll (Linux 2.6+), rt signals (Linux 2.2.19+), /dev/poll (Solaris 7 11/99+), select and poll.
  • sendfile() system call support: sendfile (FreeBSD 3.1+), sendfile (Linux 2.2+), sendfile64 (Linux 2.4.21+) and sendfilev (Solaris 8 7/01+).
  • Accept-filters support on FreeBSD 4.1+ and TCP_DEFER_ACCEPT on Linux 2.4+.
  • Very efficient memory handling: it needs only 2.5Mbytes of RAM for 10000 inactive keep-alive connections.
  • Minimum of memory copying operations

As an experimental feature, perl interpreper integration can be turned on in nginx.

As for my job, we are using nginx as a primary software for free hosting platforms. I have developed specific modules for banner inserting and stats calculation in nginx and now our central server can handle about 150-200Mbit/s of highly fragmented http-traffic (all files are small). I think, this is really good result bacause with any possible tunnings of Apache on the same servers we were not able to handle even 60-80Mbit/s.

IMHO, main problem of this server is lack of English documentation. As far as i know, its author is really busy and have no time to translate documentation to English. I hope, this article gave you main ideas of what nginx is and why I think that it is the best of lightweight http-servers in the world. ;-)

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