NGINX Buffer Directives Explained: Optimizing Proxy Performance

This article was originally published on bmf-tech.com.

I took notes while researching buffer sizes.

• large_client_header_buffers
  • Directive included in the ngx_http_core_module
  • Syntax: large_client_header_buffers number size;
  • Default: large_client_header_buffers 4 8k;
  • Context: http, server
  • Specifies the number and size of buffers used to read request headers from the client
  • Increasing the number increases the buffer count and memory usage (probably)
  • The maximum buffer size depends solely on size, not in the form of number×size...
• fastcgi_buffers
  • Directive included in the ngx_http_fastcgi_module
  • Syntax: fastcgi_buffers number size;
  • Default: fastcgi_buffers 8 4k|8k;
  • Context: http, server, location
  • Sets the number and size of buffers used to read responses from the FastCGI server per connection
  • size ≒ fastcgi_buffer_size is not true. It is believed to be the memory size used by the buffer...
• fastcgi_buffer_size
  • Directive included in the ngx_http_fastcgi_module
  • Syntax: fastcgi_buffer_size size;
  • Default: fastcgi_buffer_size 4k|8k;
  • Context: http, server, location
  • Sets the size of the buffer used to read the first part of the response from the FastCGI server