Sinatra/ActiveRecord can't handle simultaneous requests? - ruby

Question

This is my first Sinatra project and I'm pretty late in and I'm realizing that when make multiple requests at once that use ActiveRecord that I run into problems. If I only make one request, each one works on its own. But when I call both at once, I get failure.
So far I've narrowed it down to the problem being two ActiveRecord requests simultaneously. Maybe I'm not setting up ActiveRecord correctly? I use PostgreSQL because Heroku uses it, and am no inclined to change. (The issue happens on Heroku, too.)
Here's the log:
192.168.1.113 - - [30/Sep/2012:10:33:00 MDT] "GET /version/current?platform=android HTTP/1.1" 200 33
- -> /version/current?platform=android ActiveRecord::StatementInvalid - NoMethodError: undefined method `fields' for nil:NilClass: SELECT "rankings".* FROM "rankings" WHERE "rankings"."user_id" = 1 LIMIT 1:
/Users/zablanc/.rvm/gems/ruby-1.9.3-head#emm/gems/activerecord-3.2.7/lib/active_record/connection_adapters/postgresql_adapter.rb:667:in `block in exec_query'
...
Warning! Rack::Session::Cookie data size exceeds 4K.
Warning! Rack::Session::Cookie failed to save session. Content dropped.
192.168.1.113 - - [30/Sep/2012:10:33:01 MDT] "GET /badges/all HTTP/1.1" 200 311
- -> /badges/all
192.168.1.113 - - [30/Sep/2012:10:33:01 MDT] "GET /moves/ranking/all HTTP/1.1" 500 166185
- -> /moves/ranking/all
I have no idea how to shut up those cookie warnings, tho they seem to have no effect on the app. Here's how I configure my app (in a config file I require from the main script):
enable :logging
use ActiveRecord::ConnectionAdapters::ConnectionManagement
use Rack::Session::Cookie, :key => 'rack.session',
:path => '/',
:expire_after => 31_536_000, # In seconds
:secret => 'jeowkfj...secret...kjn5'
ActiveRecord::Base.include_root_in_json = false
def establish_connection(url)
db = URI.parse(url)
ActiveRecord::Base.establish_connection(
:adapter => db.scheme == 'postgres' ? 'postgresql' : db.scheme,
:host => db.host,
:port => db.port,
:username => db.user,
:password => db.password,
:database => db.path[1..-1],
:encoding => 'utf8'
)
end
configure :development do
establish_connection('postgres://postgres:postgres#localhost:5432/emm')
end
configure :test do
establish_connection('postgres://postgres:postgres#localhost:5432/emm-test')
end
configure :production do
establish_connection(ENV['DATABASE_URL'])
end
I'm guessing I'm not setting up ActiveRecord right, but I think it's just like the tutorials I've seen. What gives?

Answer 1

Sounds like you are using threads but have some non-thread-safe code in your application.
Which webserver are you using, which middleware are you using, which postgresql gem are you using, did you check to see that all your gems are thread-safe?