ruby daemons

Ruby DaemonsCreston JamisonRuby Tree Software, Inc.

GAMEhud

HTTP API accepts event and player based data from game clients.

Incoming data needs to be distributed between 10-20 tables.

Don’t want to do that in the request. Need to do background processing!

1. Reliability2. Speed

Background Processing Options Delayed Job Beanstalkd Resque Sidekiq Queue Classic Daemons

Delayed Job

Uses rake Uses full rails environment Best for long running and infrequent

jobs

Beanstalkd

Fast queue Does not poll Good for raw speed Authentication and queue

management ?

Resque

Redis based queue system Requires Redis Comes with an admin interface Uses polling

Sidekiq

Redis based queue system Requires Redis Comes with an admin interface Uses polling Uses threads Code needs to be thread safe

Queue Classic

Postgres based queue system Requires postgresql Avoids separate queue process Can avoid polling

Queue vs. Worker

Daemons

Converts a script into a daemon Not a queue system A way to create a worker process

What is a daemon?

A computer program that runs as a background process

Daemon processes typically end in ‘d’

For example: sshd

Setting up a daemon

Install daemons gem Create a control file

event_worker_control.rb Create a loop in the script called by the

control fileevent_worker.rb

Create a control file

require 'rubygems'require 'bundler/setup' require 'daemons'

Daemons.run('lib/daemons/event_worker.rb')

Loop in your script

$: << File.expand_path(".", File.dirname(__FILE__))

require ‘event_processor'

event_processor = EventProcessor.new

loop do event_processor.process sleep(5)end

Control your daemon

ruby daemon-name_control.rb start ruby daemon-name_control.rb restart ruby daemon-name_control.rb stop

ruby lib/daemons/event_worker_control.rbstart -- production

PID file

Capistrano

before 'deploy:update_code', 'deploy:stop_workers'

desc "Stop the worker processes“

task :stop_workers, :roles => :app do

run "cd #{current_path};

ruby lib/daemons/event_worker_control.rb

stop -- production“

end

Gotchas

Need rock solid error handling Otherwise your process dies Need a way to skip over errors and

come back to them

Extra Creditjstorimer.com/2012/04/19/daemon-processes-in-ruby.html

labs.headlondon.com/2010/07/skinny-daemons/

Questions?Creston Jamison@crestonjamison

creston.jamison@rubytreesoftware.com