ActiveRecord connection does not reconnect when using Thin/Sinatra but works fine with just Sinatra.

#101

I have a very simple model for a simple web service. Any call to model will throw 500, like Model.find(:first) after 10 seconds.

Error:

application error
ActiveRecord::StatementInvalid at /leads
Mysql::Error: MySQL server has gone away: SELECT * FROM leads

Setting this in model does not help:

  before do

 ActiveRecord::Base.connection.verify!

end

I have set MySQL to 10 seconds timeout to duplicate the issue quickly using this:

SET GLOBAL wait_timeout=10;
SET GLOBAL interactive_timeout=10; 
SET SESSION wait_timeout=10;
SET SESSION interactive_timeout=10;

show GLOBAL VARIABLES like 'wait_timeout'; 
show GLOBAL VARIABLES like 'interactive_timeout';
show SESSION VARIABLES like 'wait_timeout';
show SESSION VARIABLES like 'wait_timeout';

If I use rackup on the Sinatra app, no problem. When I use thin I receive the error. Here is my thin config:

--- 
pid: tmp/pids/thin.pid
log: log/thin.log
timeout: 30
port: 4600
max_conns: 1024
chdir: /Users/hbeaver/code/primedia/service_leads/
rackup: /Users/hbeaver/code/primedia/service_leads/config.ru
max_persistent_conns: 512
environment: development
daemonize: true
address: 0.0.0.0
require: []

servers: 1

Thanks,
Hank

leads_service_stacktrace.zip 47.3 KB

Reported by hbeaver (at gmail) · May 28th, 2009 @ 03:37 PM

Activity

hbeaver (at gmail)
RESOLUTION?

I moved the "before do" into extended Sinatra::Default class as opposed to model and issue was resolved. However, this does not explain why mongrel will create a new connection auto-magically whereas thin will not. Please see 2 attached tcpdumps named appropriately, 'thin_no_reconnect_example.dump' and 'mongrel_reconnect_example.dump'.

In both, the server has just been started and then a HTTP request is made to a one line action that does Model.find(:first). In both, a mysql connection is created ok after server is started. After approx. 10 seconds (because of the wait_timeout setting in the ticket I mentioned yesterday) mysql will sent a FIN/ACK (disconnect). Shortly thereafter another HTTP request is made to server. Mongrel creates yet another connection, but thin will not. I am not certain if this is a bug or just the nature of thin.

I thought it important to present this information.

Thanks again,
Hank
- thin_mongrel_tcpdumps.zip 47.2 KB
May 29th, 2009 @ 06:18 PM
Nate Wiger
I'm running into this exact same problem with thin/sinatra. Don't see it with thin/rails.

Any ideas?

August 10th, 2009 @ 12:44 PM
hbeaver (at gmail)
- Assigned user cleared.
As mentioned above, I resolved this issue by moving ActiveRecord::Base.connection.verify! into Sinatra class before do block:
```
class NewApp < Sinatra::Default   

  before do
    ActiveRecord::Base.connection.verify!
  end
...
end #end of Sinatra class
```
August 10th, 2009 @ 01:05 PM
Nate Wiger
- Assigned user set to macournoyer
Just to follow-up, this approach has been working for me for some time. Based on the AR docs, the "correct" call which will handle multiple connections, etc, is:
```
before do
  ActiveRecord::Base.verify_active_connections!
end
```
I'm not sure if this is a bug in Thin per se, but it would still be interesting to understand why this happens with Thin/Sinatra as opposed to Mongrel or Thin/Rails.
June 24th, 2010 @ 10:17 AM
Conny Brunnkvist
- Milestone order changed from 0 to 0
Same problem here.

Works when running in foreground but as soon as either of "-s 1" or "servers: 1" is set, ActiveRecord is can't connect.

July 21st, 2010 @ 07:15 PM
Conny Brunnkvist
I wonder if we don't need to simply ActiveRecord::Base.establish_connection after forking.. but then, why wouldn't reconnect! work? I gave up on this one, will try again later perhaps.

July 26th, 2010 @ 12:22 PM

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