deadlock?

[analytically]

2014/09/29 19:27:13 Listening on 127.0.0.1:666
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [IO wait]:
net.runtime_pollWait(0x7fbe378d7618, 0x72, 0x0)
        /usr/lib/go/src/pkg/runtime/netpoll.goc:116 +0x6a
net.(*pollDesc).Wait(0xc2100537d0, 0x72, 0x7fbe378d60e8, 0xb)
        /usr/lib/go/src/pkg/net/fd_poll_runtime.go:81 +0x34
net.(*pollDesc).WaitRead(0xc2100537d0, 0xb, 0x7fbe378d60e8)
        /usr/lib/go/src/pkg/net/fd_poll_runtime.go:86 +0x30
net.(*netFD).accept(0xc210053770, 0x72cd18, 0x0, 0x7fbe378d60e8, 0xb)
        /usr/lib/go/src/pkg/net/fd_unix.go:382 +0x2c2
net.(*TCPListener).AcceptTCP(0xc210000250, 0x18, 0xc21000b810, 0x44c713)
        /usr/lib/go/src/pkg/net/tcpsock_posix.go:233 +0x47
net.(*TCPListener).Accept(0xc210000250, 0x7fbe378d65f8, 0xc21001ec00, 0x0, 0x0)
        /usr/lib/go/src/pkg/net/tcpsock_posix.go:243 +0x27
net/http.(*Server).Serve(0xc21001f500, 0x7fbe378d6650, 0xc210000250, 0x0, 0x0)
        /usr/lib/go/src/pkg/net/http/server.go:1622 +0x91
net/http.(*Server).ListenAndServe(0xc21001f500, 0xc21001f500, 0x1b)
        /usr/lib/go/src/pkg/net/http/server.go:1612 +0xa0
net/http.ListenAndServe(0x7fffe4217d5c, 0xd, 0x0, 0x0, 0x1, ...)
        /usr/lib/go/src/pkg/net/http/server.go:1677 +0x6d
main.main()
        /usr/share/go/src/github.com/bketelsen/captainhook/main.go:34 +0x321
2014/09/29 19:27:13 Listening on 127.0.0.1:667

[bketelsen]

why do you have two different ports listening? Looks like 666 and 667?

[analytically]

I'm running CaptainHook on Docker with autorestart=true. So to be able to run CaptainHook in multiple containers on the same machine with --net=host Docker, I use

#!/bin/bash

increment=${CAPTAINHOOK_PORT_INCREMENT:-1}
port=${CAPTAINHOOK_PORT:-666}

isfree=$(netstat -tapln | grep $port)
while [[ -n "$isfree" ]]; do
  port=$[port+increment]
  isfree=$(netstat -tapln | grep $port)
done

exec /usr/share/gocode/bin/captainhook -listen-addr 127.0.0.1:$port -configdir /etc/captainhook -echo

Hence the 2014/09/29 19:27:13 Listening on 127.0.0.1:667 line.

[analytically]

So basically, I think this goes like: bind to 666, crash without releasing the bind, bind on 667.

[analytically]

PS this is on Ubuntu 14.04 using Go 1.2.1.

[bketelsen]

It's deadlocked because the port is in use. Your incrementing script might have a bug?

[analytically]

Hmm this is running on a machine with only one Docker container running, so the port wasn't in use. I can also see that by the 2014/09/29 19:27:13 Listening on 127.0.0.1:666 line. If the port was in use, it would not have bound to it.

[bketelsen]

it didn't bind to it, that's line 34 in your stack trace. Go is waiting for that port to be freed.