The HTTP accept loop parked on acquire_owned() when the connection
budget drained, freezing accept() for every client (the .228
session-flapping / CLOSE-WAIT signature). Permits drained because
half-open clients and hung upstreams held them indefinitely.
- try_acquire_owned + immediate 503-and-close when the budget is
exhausted; the accept loop itself never blocks
- 30s http1_header_read_timeout drops slowloris/half-open clients
- 900s watchdog bounds non-upgraded connections; websocket upgrades
are exempt (legitimately long-lived)
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>