Caddy stops serving http and grpc under heavy grpc-web traffic

[pokaichen]

Caddy 0.11.0, compiled for armv7 with grpc-web plugin.

Steps to reproduce: 1) Start with example code from improbable-eng: https://github.com/improbable-eng/grpc-web/blob/master/example/ts/src/index.ts 2) Replace the call to queryBooks(); with a recursive call to if (status !== 14) getBook(); Change IP to caddy's server IP. 3) Start grpc service (server) 4) Run caddy with config 0.0.0.0:8080, localhost:8080 { } 0.0.0.0:55552, localhost:55552 { grpc 10.0.4.32:9090 { backend_is_insecure backend_tls_noverify } } At this point, both the http server and grpc-web proxy is up. 5) Open browser and load index.html. 6) After ~1061 calls to getBook(), http server and grpc-web proxy will no longer respond. Specific number of requests (including index.html and bundle.js) until we get a return status of 14: 1016,951,1061,1061,1061,1020,1016. 7) At this point, the caddy process is still running, but neither the http server or the grpc-web server works. getBook responds with: getBook.onEnd.status 14 all SubConns are in TransientFailure, latest connection error: connection error: desc = "transport: Error while dialing dial tcp 127.0.0.1:60000: socket: too many open files"

[met-pub]

maybe this is the same reason: It seems caddy still hold the connection to server.