# MySQL has gone away

**URL:** <https://www.ruby-forum.com/t/mysql-has-gone-away/113657>\
**Category:** Ferret\
**Created:** [September 3, 2007, 3:42pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657 "2007-09-03T15:42:07Z")\
**Posts on this page:** 14\
**Page:** 1

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 3, 2007, 3:42pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/1 "2007-09-03T15:42:07Z")

</div>

Hi,

in a production environment we are running into “MySQL server has gone  
away” errors (see below) when we call rebuild\_index in aaf. This happens  
sporadically.

Any suggestions for what might be wrong or workarounds? I guess we try a  
reconnect before we call rebuild\_index?

Matthew

ActiveRecord::StatementInvalid (Mysql::Error: MySQL server has gone  
away: SELECT count(\*) AS count\_all FROM bands ):  
(druby://localhost:3009)  
/usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active\_record/connection\_adapters/abstract\_adapter.rb:128:in  
`log' (druby://localhost:3009) /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/mysql_adapter.rb:243:in`execute’  
(druby://localhost:3009)  
/usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active\_record/connection\_adapters/mysql\_adapter.rb:399:in  
`select' (druby://localhost:3009) /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/abstract/database_statements.rb:13:in`select\_one’  
(druby://localhost:3009)  
/usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active\_record/connection\_adapters/abstract/database\_statements.rb:19:in  
`select_value' (druby://localhost:3009) /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/calculations.rb:212:in`execute\_simple\_calculation’  
(druby://localhost:3009)  
/usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active\_record/calculations.rb:121:in  
`calculate' (druby://localhost:3009) /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/calculations.rb:117:in`catch’  
(druby://localhost:3009)  
/usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active\_record/calculations.rb:117:in  
`calculate' (druby://localhost:3009) /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/calculations.rb:45:in`count’  
(druby://localhost:3009)  
/var/www/web1/oms/current/script/…/config/…/vendor/plugins/acts\_as\_ferret/lib/ferret\_extensions.rb:22:in  
`index_model' (druby://localhost:3009) /var/www/web1/oms/current/script/../config/../vendor/plugins/acts_as_ferret/lib/ferret_extensions.rb:9:in`index\_models’  
(druby://localhost:3009)  
/var/www/web1/oms/current/script/…/config/…/vendor/plugins/acts\_as\_ferret/lib/ferret\_extensions.rb:9:in  
`each' (druby://localhost:3009) /var/www/web1/oms/current/script/../config/../vendor/plugins/acts_as_ferret/lib/ferret_extensions.rb:9:in`index\_models’  
(druby://localhost:3009)  
/var/www/web1/oms/current/script/…/config/…/vendor/plugins/acts\_as\_ferret/lib/ferret\_server.rb:93:in  
`rebuild_index' (druby://localhost:3009) /var/www/web1/oms/current/script/../config/../vendor/plugins/acts_as_ferret/lib/ferret_server.rb:113:in`with\_class’  
(druby://localhost:3009)  
/var/www/web1/oms/current/script/…/config/…/vendor/plugins/acts\_as\_ferret/lib/ferret\_server.rb:88:in  
`rebuild_index' /vendor/plugins/acts_as_ferret/lib/remote_index.rb:16:in`send’  
/vendor/plugins/acts\_as\_ferret/lib/remote\_index.rb:16:in  
`method_missing' /vendor/plugins/acts_as_ferret/lib/class_methods.rb:15:in`rebuild\_index’

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 3, 2007, 3:52pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/2 "2007-09-03T15:52:27Z")

</div>

I need to add that we are running the integrated aaf Ferret Drb Server,  
so I guess it is the Drb Server that is losing the connection? How can I  
get it to reconnect without throwing the error?

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 3, 2007, 4:12pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/3 "2007-09-03T16:12:40Z")

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On 2007-09-03, at 3:52 PM, Matthew L.ham wrote:

> I need to add that we are running the integrated aaf Ferret Drb  
> Server,  
> so I guess it is the Drb Server that is losing the connection? How  
> can I  
> get it to reconnect without throwing the error?

Hey …

we’ve got the same error with our non-aaf backgroundrb solution …

that’s what we’re doing:

begin  
index\_object( record )  
rescue ActiveRecord::RecordNotFound  
@logger.warn “Object gone”  
rescue ActiveRecord::StatementInvalid  
@logger.warn “MySQL is gone…”  
clazz.connection.reconnect!  
enqueue\_object( record )  
end

So basically just catch the StatementInvalid Exception and  
try again after you reconnected to the database…

I guess Jens can add something like that to AAF quite easily 🙂

Ben

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 3, 2007, 4:28pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/4 "2007-09-03T16:28:42Z")

</div>

> Setting ActiveRecord::Base.allow\_concurrency to true solved this  
> problem for me once, however I’m not sure why and it was not  
> ferret-related.

We set the following … but still - the sql connection is lost from time  
to time…

ActiveRecord::Base.allow\_concurrency = true  
ActiveRecord::Base.verification\_timeout = 10

Ben

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 4, 2007, 12:23am UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/5 "2007-09-04T00:23:26Z")

</div>

Are you running Ubuntu?

If yes, try installing the libmysqlclient-dev package (latest one you  
have), then run “sudo gem install mysql”. You get my meaning. If  
you’re not running Ubuntu, get the mysql client development headers,  
which are required by the mysql gem, then install the gem.

I had a similar issue to yours, then I installed the C based  
extensions. Problem went away.

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 3, 2007, 4:22pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/6 "2007-09-03T16:22:41Z")

</div>

Hi!

On Mon, Sep 03, 2007 at 03:42:07PM +0200, Matthew L.ham wrote:

> Hi,
> 
> in a production environment we are running into “MySQL server has gone  
> away” errors (see below) when we call rebuild\_index in aaf. This happens  
> sporadically.

Does it happen after a long time of inactivity on the DRb server’s side?

If yes, a look at mysql’s wait\_timeout setting, and  
ActiveRecord::Base.verification\_timeout, wich should be less than the  
former, might help.

Setting ActiveRecord::Base.allow\_concurrency to true solved this  
problem for me once, however I’m not sure why and it was not  
ferret-related.

Cheers,  
Jens

–  
Jens Krämer  
webit! Gesellschaft für neue Medien mbH  
Schnorrstraße 76 | 01069 Dresden  
Telefon +49 351 46766-0 | Telefax +49 351 46766-66  
removed\_email\_address@domain.invalid | [www.webit.de](http://www.webit.de)

Amtsgericht Dresden | HRB 15422  
GF Sven Haubold, Hagen Malessa

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 4, 2007, 9:34am UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/7 "2007-09-04T09:34:58Z")

</div>

> I had a similar issue to yours, then I installed the C based  
> extensions. Problem went away.

Julio,

i got the mysql bindings (version 2.7) installed. But there is a newer  
version (2.7.3). I will update them and take a look. Thanks for the  
suggestion 🙂

Ben

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 4, 2007, 1:35pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/8 "2007-09-04T13:35:51Z")

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On 03.09.2007, at 16:27, Benjamin K. wrote:

> > Setting ActiveRecord::Base.allow\_concurrency to true solved this  
> > problem for me once, however I’m not sure why and it was not  
> > ferret-related.
> 
> ActiveRecord::Base.allow\_concurrency = true  
> ActiveRecord::Base.verification\_timeout = 10

ActiveRecord just isn’t reentrant. Period 😉

There are supposedly ways to make it work using allow\_concurrency,  
reconnect and whatever. But…

> … but still - the sql connection is lost from time to time…

Exactly.

I rebuild my index in a separate process and directory. When it’s  
done, I tell the index server via DRb that a new index is available  
and it’ll switch to the new directory. Works like a charm.

Cheers,  
Andy

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 5, 2007, 11:10pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/9 "2007-09-05T23:10:16Z")

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On Mon, Sep 03, 2007 at 04:11:34PM +0200, Benjamin K. wrote:

> clazz.connection.reconnect!  
> enqueue\_object( record )  
> end
> 
> So basically just catch the StatementInvalid Exception and  
> try again after you reconnected to the database…
> 
> I guess Jens can add something like that to AAF quite easily 🙂

Okay, I just committed this. According to my limited testing it works as  
intended - close db connection with Model.connection.disconnect, and it  
will reconnect again.

Please give it a try and report the outcome here 🙂

cheers,  
Jens

–  
Jens Krämer  
[http://www.jkraemer.net/](http://www.jkraemer.net/) - Blog  
[http://www.omdb.org/](http://www.omdb.org/) - The new free film database

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [September 6, 2007, 12:36pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/10 "2007-09-06T12:36:31Z")

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On 05.09.2007, at 18:40, Ed – wrote:

> > I rebuild my index in a separate process and directory. When it’s  
> > done, I tell the index server via DRb that a new index is available  
> > and it’ll switch to the new directory. Works like a charm.
> 
> Do you use backgroundrb for this?. I’m coming up against similar  
> problems with long running processes which need an ActiveRecord  
> connection. I briefly tried to use fork() to background it but that  
> seemed to give me problems with acts-as-authenticated.

I use fork without problems. Here’s a snippet from my controller  
which triggers the rebuild:

```
 def exec_command(command)
   dbconfig = ActiveRecord::Base.remove_connection
   fork do
     begin
       ActiveRecord::Base.establish_connection(dbconfig)
       `cd #{RAILS_ROOT} && script/runner -e #{ENV['RAILS_ENV']}

```

‘#{index\_class}.#{command}’`  
ensure  
ActiveRecord::Base.remove\_connection  
end  
end  
ActiveRecord::Base.establish\_connection(dbconfig)  
end

As you can see, I’m actually running a shell script which starts a  
whole new Rails process via script/runner. Note that  
ActiveRecord::Base.allow\_concurrency is NOT set to true.

I don’t remember why this remove/establish connection was necessary,  
but it’s definitely needed.

Cheers,  
Andy

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**Post date:** [September 5, 2007, 6:40pm UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/11 "2007-09-05T18:40:17Z")

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Andreas K. wrote:

> I rebuild my index in a separate process and directory. When it’s  
> done, I tell the index server via DRb that a new index is available  
> and it’ll switch to the new directory. Works like a charm.

Do you use backgroundrb for this?. I’m coming up against similar  
problems with long running processes which need an ActiveRecord  
connection. I briefly tried to use fork() to background it but that  
seemed to give me problems with acts-as-authenticated.

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [August 27, 2008, 5:55am UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/12 "2008-08-27T05:55:34Z")

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Ken Wei wrote:

> I did a hack in the abstract connection code to enable the  
> auto-reconnection property.  
> Hi Ken,

Where would this hack go? I am not sure I understand what you did there.

---

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**Post date:** [September 11, 2007, 9:12am UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/13 "2007-09-11T09:12:04Z")

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I did a hack in the abstract connection code to enable the  
auto-reconnection property.

---

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**Author:** ![turnkeytraders](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ba8739/32.png) [@turnkeytraders](https://www.ruby-forum.com/u/turnkeytraders)\
**Post date:** [August 27, 2008, 6:00am UTC](https://www.ruby-forum.com/t/mysql-has-gone-away/113657/14 "2008-08-27T06:00:24Z")

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Bruno Miranda wrote:

> Ken Wei wrote:
> 
> > I did a hack in the abstract connection code to enable the  
> > auto-reconnection property.  
> > Hi Ken,
> 
> Where would this hack go? I am not sure I understand what you did there.

module ActiveRecord  
class Base

```
class << self
  alias :old_connection :connection
  def connection
    self.verify_active_connections!
    old_connection
  end
end

```

end  
end