what is worker_processes and worker_connections in Nginx?

worker_connections is the number of simultaneous connections; so they are simply stating how to calculate, for example:

• you are only running 1 process with 512 connections, you will only be able to serve 512 clients.

• If 2 processes with 512 connections each, you will be able to handle 2x512=1024 clients.

The number of connections is limited by the maximum number of open files (RLIMIT_NOFILE) on your system

nginx has a better, updated description of worker connections.

fyi, the wiki section is considered obsolete (dont ask), now only the main nginx.org/en/docs are preferred...

• Worker processes:

  • Nginx worker process that handles the incoming request.
  • Set this to worker_process auto; to automatically adjust the number of Nginx worker processes based on available cores.
  • This can go beyond the available cores if you have IO access.

• Worker connections:

  • Each worker process can open by default 512 connections.
  • You can change this limit by worker_connections <no>.
  • You can set this to max limit ulimit -n.
  • hence,

  max_clients = worker processes * worker connections