Failed to start DRB: port already in use

[JustinAiken]

I've occasionally seen adhearsion-drb fail to initialize, both legitimately (something already had the port), or freakishly randomly. No log at the moment, I'll try to capture one next time I see a random fail...

But, if it does fail, it just logs a one-line error, and the adhearsion up starts up normally. Most applications using adhearsion-drb probably rely on it for core functionallity, so I think adhearsion-drb should either:

• Keep trying to start the service upon failure
• Prevent ahn from starting up at all (if options are enabled)
• Something else?

Any thoughts about better failure handling?

[benlangfeld]

I'll come back to better handling the failure later. For now, how are you ascertaining that nothing is holding the port?

[JustinAiken]

If I kill ahn and immediately start it again, it works.. thought it was a Vagrant networking thing while I was developing it, but also seeing it on a live staging server too.

[benlangfeld]

How do you kill ahn? killall ahn, or targeted at a particular PID?

[JustinAiken]

In development, ctrl-c, in staging restarting it with God, which executes:

"cd #{@talkbox_path} && bundle exec ahn stop . && bundle exec ahn daemon ."

[JustinAiken]

[2013-11-12 16:25:19] INFO  Adhearsion::Drb::Plugin::Service: Starting DRb on 0.0.0.0:9050
[2013-11-12 16:25:19] DEBUG Celluloid: Terminating 4 actors...
[2013-11-12 16:25:19] DEBUG Punchblock::Connection::Asterisk: Finalizing stream
/usr/local/lib/ruby/1.9.1/drb/drb.rb:861:in `initialize': Address already in use - bind(2) (Errno::EADDRINUSE)
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:861:in `open'
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:861:in `open_server'
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:759:in `block in open_server'
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:757:in `each'
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:757:in `open_server'
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:1342:in `initialize'
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:1624:in `new'
    from /usr/local/lib/ruby/1.9.1/drb/drb.rb:1624:in `start_service'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-drb-1.0.0/lib/adhearsion/drb/plugin/service.rb:19:in `start'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-drb-1.0.0/lib/adhearsion/drb/plugin.rb:27:in `block in <class:Plugin>'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/plugin/initializer.rb:26:in `instance_exec'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/plugin/initializer.rb:26:in `run'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/plugin.rb:168:in `block in init_plugins'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/plugin.rb:167:in `each'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/plugin.rb:167:in `init_plugins'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/initializer.rb:229:in `init_plugins'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/initializer.rb:61:in `block in start'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/initializer.rb:41:in `catch'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/initializer.rb:41:in `start'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/initializer.rb:12:in `start'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/cli_commands/ahn_command.rb:103:in `start_app'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/adhearsion-2.4.0/lib/adhearsion/cli_commands/ahn_command.rb:48:in `daemon'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/thor-0.18.1/lib/thor/command.rb:27:in `run'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/thor-0.18.1/lib/thor/invocation.rb:120:in `invoke_command'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/thor-0.18.1/lib/thor.rb:363:in `dispatch'
    from /data/apps/talkbox/shared/bundle/ruby/1.9.1/gems/thor-0.18.1/lib/thor/base.rb:439:in `start'
    from script/ahn:9:in `<main>'

[bklang]

This implies some other process already has the port open. Is it possible that you have another instance of Adhearsion (perhaps not quite shutdown) still running? Even another Ruby process using DRb on the same port?

[JustinAiken]

No other ahn running at the time... forgot to netstat when it happened to see if anything listening to the port, will next time it occurs.