mongrel unicorn - Aug 2012 - after_fork - ActiveRecord::AdapterNotSpecified

Hi all,

I''m fighting with the after_fork hook and my sinatra application. The
Sinatra app is using active_record,
In my unciron.rb file I''m using 
preload_app true
after_fork do |server, worker|
? defined?(ActiveRecord::Base) and
??? ActiveRecord::Base.establish_connection
End

but I always get the error:
ERROR -- : ActiveRecord::AdapterNotSpecified (ActiveRecord::AdapterNotSpecified)

I''m using unicorn (4.3.1), sinatra (1.3.2), activerecord (3.2.6), ruby
1.9.3p194

The app (test.rb):
require ''rubygems''
require ''sinatra''
require ''active_record''

ActiveRecord::Base.establish_connection(
? :adapter => ''sqlite3'',
? :database => ''/tmp/dbfile''
)

class User < ActiveRecord::Base
end

get ''/'' do
? @users = User.all
? "This is a Sinatra test. We have #{@users.count} users."
end

The config.ru
require ''./test''
run Sinatra::Application
The config/unicorn.rb
@dir = ''/home/frankr/tmp/sinatra/''
pidfile = " #{@dir}log/unicorn.pid"

worker_processes 3
preload_app true
GC.respond_to?(:copy_on_write_friendly=) and GC.copy_on_write_friendly = true

timeout 30
listen ''/tmp/sinatra.socket'', :backlog => 64
pid pidfile
stderr_path "#{@dir}log/unicorn.stderr.log"
stdout_path "#{@dir}log/unicorn.stdout.log"

before_fork do |server, worker|
? defined?(ActiveRecord::Base) and
??? ActiveRecord::Base.connection.disconnect!
? end
end

after_fork do |server, worker|
? defined?(ActiveRecord::Base) and
??? ActiveRecord::Base.establish_connection
end

when I start? unicorn
??? unicorn -c config/unicorn.rb -E production -D -l 0.0.0.0:3001
the unicorn.stderr.log file is growing and growing and repeating the same error
message:
.
E, [2012-08-31T07:18:39.232254 #29793] ERROR -- :
ActiveRecord::AdapterNotSpecified (ActiveRecord::AdapterNotSpecified)
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/activerecord-3.2.6/lib/active_record/connection_adapters/abstract/connection_specification.rb:22:in
`spec''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/activerecord-3.2.6/lib/active_record/connection_adapters/abstract/connection_specification.rb:127:in
`establish_connection''
config/unicorn.rb:54:in `block in reload''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:565:in
`call''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:565:in
`init_worker_process''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:589:in
`worker_loop''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:487:in
`spawn_missing_workers''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:137:in
`start''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/bin/unicorn:121:in
`<top (required)>''
/home/frankr/.rbenv/versions/1.9.3-p194/bin/unicorn:23:in `load''
/home/frankr/.rbenv/versions/1.9.3-p194/bin/unicorn:23:in
`<main>''
I, [2012-08-31T07:18:39.232514 #29790]? INFO -- : master process ready
E, [2012-08-31T07:18:39.232758 #29796] ERROR -- :
ActiveRecord::AdapterNotSpecified (ActiveRecord::AdapterNotSpecified)
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/activerecord-3.2.6/lib/active_record/connection_adapters/abstract/connection_specification.rb:22:in
`spec''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/activerecord-3.2.6/lib/active_record/connection_adapters/abstract/connection_specification.rb:127:in
`establish_connection''
config/unicorn.rb:54:in `block in reload''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:565:in
`call''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:565:in
`init_worker_process''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:589:in
`worker_loop''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:487:in
`spawn_missing_workers''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/lib/unicorn/http_server.rb:137:in
`start''
/home/frankr/.rbenv/versions/1.9.3-p194/lib/ruby/gems/1.9.1/gems/unicorn-4.3.1/bin/unicorn:121:in
`<top (required)>''
/home/frankr/.rbenv/versions/1.9.3-p194/bin/unicorn:23:in `load''
/home/frankr/.rbenv/versions/1.9.3-p194/bin/unicorn:23:in
`<main>''
E, [2012-08-31T07:18:39.232976 #29790] ERROR -- : reaped #<Process::Status:
pid 29793 exit 1> worker=0
.


I get the same error, when using different database adapter. On the other hand
everything is working fine, when repeating the database configuration in
after_fork hook, or completely remove database configuration from Sinatra app
into after_fork hook. But this is not a solution for me. First I don''t
like to double code, second I need the database configuration in the Sinatra app
for running tests .

My question is what am I doing wrong? All documentation says that 
??defined?(ActiveRecord::Base) and
??? ActiveRecord::Base.establish_connection
? end
should work.

Regards,
Frank

Frank Rennekamp <frank.rennekamp at dataroomservices.com>
wrote:
> Hi all,
> 
> I''m fighting with the after_fork hook and my sinatra application.
The Sinatra app is using active_record,
> In my unciron.rb file I''m using 
> preload_app true
<snip>
> I get the same error, when using different database adapter. On the
> other hand everything is working fine, when repeating the database
> configuration in after_fork hook, or completely remove database
> configuration from Sinatra app into after_fork hook. But this is not a
> solution for me. First I don''t like to double code, second I need
the
> database configuration in the Sinatra app for running tests .
I agree, none of those solutions seem good.
> My question is what am I doing wrong? All documentation says that 
> ??defined?(ActiveRecord::Base) and
> ??? ActiveRecord::Base.establish_connection
> ? end
> should work.
I''m not familiar with Rails nowadays, but from reading the Rails 3.2.6
source/docs, I believe calling ActiveRecord::Base.establish_connection
(without arguments) only works with a Rails environment.

Perhaps a Rails DB config file (config/database.yml) is all that''s
needed, you could try that.

For the ultimate in DRY-ness, perhaps putting the logic in a before
block for your Sinatra app:
--------------------------------- 8< --------------------------------
# use a Mutex in case this gets used on a multi-threaded server
# (something other than unicorn)
db_lock = Mutex.new
db_connected = false

before do
  db_lock.synchronize do
    unless db_connected
      ActiveRecord::Base.establish_connection(
      ? :adapter => ''sqlite3'',
      ? :database => ''/tmp/dbfile''
      )
      db_connected = true
    end
  end
end
--------------------------------- 8< --------------------------------

The above example should work regardless of which Rack server you
choose, and I think the per-request overhead will be negligible.

I''d also be interested to hear anybody elses'' experiences and
recommendations for combining Sinatra + ActiveRecord with unicorn.