Web Servers: Architecture and Tuning

Web servers are the front line for delivering pages and APIs. They manage many client connections, parse requests, and send responses fast. A good architecture balances speed, reliability, and resources. The right setup depends on traffic patterns, latency goals, and hardware.

Key architecture patterns:

  • Event-driven, single process models handle many connections with a small memory footprint.
  • Multi-process or multi-threaded models offer isolation and simplicity, at the cost of more memory.
  • Reverse proxies and load balancers sit in front, distributing work and improving resilience.
  • Caching proxies and CDN links reduce repeated work and speed up responses.
  • TLS termination can take crypto work away from backends and simplify certificates.

Tuning areas you can tune without changing applications:

  • Operating system limits: raise the number of file descriptors and adjust backlog settings.
  • Network and kernel: set somaxconn and tune timeouts to avoid slow closes or stalls.
  • Server worker model: match workers to CPU cores and RAM. For NGINX, consider auto for worker_processes and a healthy number of worker_connections.
  • Timeouts and keep-alives: configure keepalive_timeout, client_header_timeout, and related limits to balance throughput and resource use.
  • TLS and HTTP features: prefer modern protocols (HTTP/2, HTTP/3 where possible) and enable session reuse; choose strong, efficient ciphers.
  • Caching and compression: enable gzip or Brotli where appropriate; send effective cache headers to reduce repeated work.
  • Logging and monitoring: track latency, error rates, request rates, and resource usage to spot bottlenecks early.

Practical examples you can apply:

  • NGINX: set worker_processes to auto and increase worker_connections to 1024; use a modest keepalive_timeout like 15 seconds to keep connections useful without starving resources.
  • Apache: if you use the Event MPM, tune StartServers and MinSpareThreads, and set ThreadsPerChild and MaxRequestWorkers to balance memory and concurrency.
  • System tuning: raise file descriptors (ulimit -n) and adjust net.core/somaxconn to support larger queues during traffic spikes.

A well-tuned web server is built from measured decisions. Start with load patterns, apply conservative defaults, and monitor results after each change.

Key Takeaways

  • Architecture choices shape how your server handles concurrency and load.
  • OS, kernel, and server settings must align with hardware and traffic.
  • Use caching, TLS best practices, and modern HTTP features to improve performance.