nginx resource_error ai_generated true

nginx: [alert] 1024 worker_connections are not enough

ID: nginx/worker-connections-exceeded

Also available as: JSON · Markdown
90%Fix Rate
90%Confidence
3Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1 active — — —
1 active — — —

Root Cause

nginx worker process ran out of connection slots. Default 1024 is too low for high-traffic sites.

generic

Workarounds

  1. 92% success Increase worker_connections to match expected concurrency 
    events { worker_connections 4096; }  # in nginx.conf; rule of thumb: 2-4x expected concurrent connections

    Sources: https://nginx.org/en/docs/http/ngx_http_core_module.html

  2. 90% success Increase OS file descriptor limits 
    In /etc/security/limits.conf: nginx soft nofile 65536; nginx hard nofile 65536; also: worker_rlimit_nofile 65536; in nginx.conf
  3. 82% success Enable multi_accept to handle multiple connections per event 
    events { multi_accept on; use epoll; }  # accept all pending connections at once instead of one by one

Dead Ends

Common approaches that don't work:

  1. Set worker_connections to extremely high value like 1000000 72% fail

    Each connection uses memory (~1-2KB). Unreachable high values waste kernel resources. Set based on actual peak + headroom.

  2. Only increase worker_connections without checking ulimit 85% fail

    OS file descriptor limit (ulimit -n) must be >= worker_connections. nginx cannot open more FDs than the OS allows.