Alexander Yunin sagebomb

Finding a Ruby memory leak using a time analysis

When developing a program in Ruby, you may sometimes encounter a memory leak. For a while now, Ruby has a facility to gather information about what objects are laying around: ObjectSpace.

There are several approaches one can take to debug a leak. This discusses a time-based approach, where a full memory dump is generated every, say, 5 minutes, during a time that the memory leak is showing up. Afterwards, one can look at all the objects, and find out which ones are staying around, causing the

Haskell Resources

Zero downtime deploys with unicorn + nginx + runit + rvm + chef

Below are the actual files we use in one of our latest production applications at Agora Games to achieve zero downtime deploys with unicorn. You've probably already read the GitHub blog post on Unicorn and would like to try zero downtime deploys for your application. I hope these files and notes help. I am happy to update these files or these notes if there are comments/questions. YMMV (of course).

Other application notes:

Our application uses MongoDB, so we don't have database migrations to worry about as with MySQL or postgresql. That does not mean that we won't have to worry about issues with the database with indexes being built in MongoDB or what have you.
We use capistrano for deployment.

Salient points for each file:

Ubuntu 12.10 setup (rbenv/RVM, Janus, PostgreSQL)

Basic pre-requisites

Some utilities:

sudo apt-get install vim tmux git curl

Copy/paste from the command line:

Rails Models

Generating models

$ rails g model User

Associations

belongs_to

has_one

	class TracePoint
	class Middleware

	def initialize(app)
	@app = app
	end

	def call(env)
	stats = {}
	trace = TracePoint.new(:call) do \|tp\|

	package main

	import (

	"log"
	"net/mail"
	"encoding/base64"
	"net/smtp"
	"fmt"
	"strings"

	# coding: utf-8
	require 'sinatra'
	set server: 'thin', connections: []

	get '/' do
	halt erb(:login) unless params[:user]
	erb :chat, locals: { user: params[:user].gsub(/\W/, '') }
	end

	get '/stream', provides: 'text/event-stream' do

	# app/models/ability.rb

	# All front end users are authorized using this class
	class Ability
	include CanCan::Ability

	def initialize(user)
	user \|\|= User.new

	can :read, :all

	#!/bin/bash -e
	#
	# Since unicorn creates a new pid on restart/reload, it needs a little extra love to
	# manage with runit. Instead of managing unicorn directly, we simply trap signal calls
	# to the service and redirect them to unicorn directly.
	#
	# To make this work properly with RVM, you should create a wrapper for the app's gemset unicorn.
	#

	function is_unicorn_alive {