Rails Rake task displayed execution expired message and program stopped - ruby-on-rails

Question

I have a rake task to load car's image from the table websites using paperclip. The image stored in database as a remote link.
Here is my code and i'm using ruby 1.8.7, rails 2.3.8 and DB mysql.
namespace :db do
task :load_photo => :environment do
require 'rubygems'
require 'open-uri'
require 'net/http'
require 'paperclip'
begin
images =Website.find(:all,:conditions=>["image_url is not null"])
images.each do |photo|
url = URI.parse(photo.image_url)
Net::HTTP.start(url.host, url.port) do |http|
if http.head(url.request_uri).code == "200"
Car.update_attribute(:photo,open(url))
end
end
end
rescue Exception => e
end
end
end
Run above rake task by db:load_photo. In my table (Website) has 60,000 rows. Rake task running upto 10000 rows only and execution terminated with an error message "execution expired".
Can any one help me to figure this out?
Thanks in advance.

Answer 1

You may find it more performant to run it in batches, active record has a find_in_batches method which stops loading all the records into memory at one time.
http://ryandaigle.com/articles/2009/2/23/what-s-new-in-edge-rails-batched-find
You could change your code to look like:
namespace :db do
task :load_photo => :environment do
require 'rubygems'
require 'open-uri'
require 'net/http'
require 'paperclip'
Website.find_in_batches(:conditions=>["image_url is not null"]) do |websites|
websites.each do |website|
begin
url = URI.parse(website.image_url)
Net::HTTP.start(url.host, url.port) do |http|
if http.head(url.request_uri).code == "200"
Car.update_attribute(:photo,open(url))
end
end
rescue Exception => e
end
end
end
end
end

Answer 2

I can only guess, but it looks like you're making a little DoS attack to the server you're pulling images from.
You can try to play with a little delay between sequential requests (like "sleep 1").
Also, if your "execution expired" is a Timeout::Error exception, then you can't catch it with
rescue Exception => e
because Timeout::Error is not a subclass of StandardError, it is a subclass of the Interrupt class. You have to catch it explicitly, like so:
rescue Timeout::Error => e