Rails core - May 2008 - Why don't enable auto-reconnect while database connection lost?

Hi.

Sorry for raise an old issue. I have seen the ticket in trac but no answers
found.

My database is mysql and when it''s idle for a long time, the connection
lost
and raise some exception.

I have read the mysql_adapter.rb and find it hasn''t used the reconnect
policy which is allowed by the Mysql Binding.

So why don''t enable this feature?  Is this a design choice?

I think if we allow to set "reconnect: true" in the database.yml, the
thing
will be better.

Maybe i miss something, thanks for your all advice.

Best regards.

sishen

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Should I submit a patch about this?  Thanks.

On May 13, 8:13 pm, sishen <yedingd...@gmail.com>
wrote:
> Hi.
>
> Sorry for raise an old issue. I have seen the ticket in trac but no answers
> found.
>
> My database is mysql and when it''s idle for a long time, the
connection lost
> and raise some exception.
>
> I have read the mysql_adapter.rb and find it hasn''t used the
reconnect
> policy which is allowed by the Mysql Binding.
>
> So why don''t enable this feature?  Is this a design choice?
>
> I think if we allow to set "reconnect: true" in the database.yml,
the thing
> will be better.
>
> Maybe i miss something, thanks for your all advice.
>
> Best regards.
>
> sishen
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afaik Rails runs
 ActiveRecord::Base.verify_active_connections!

before each request.  Is this broken?

On Fri, May 16, 2008 at 12:03 AM, sishen <YeDingding@gmail.com> wrote:
>
> Should I submit a patch about this?  Thanks.
>
> On May 13, 8:13 pm, sishen <yedingd...@gmail.com> wrote:
> > Hi.
> >
> > Sorry for raise an old issue. I have seen the ticket in trac but no
> answers
> > found.
> >
> > My database is mysql and when it''s idle for a long time, the
connection
> lost
> > and raise some exception.
> >
> > I have read the mysql_adapter.rb and find it hasn''t used the
reconnect
> > policy which is allowed by the Mysql Binding.
> >
> > So why don''t enable this feature?  Is this a design choice?
> >
> > I think if we allow to set "reconnect: true" in the
database.yml, the
> thing
> > will be better.
> >
> > Maybe i miss something, thanks for your all advice.
> >
> > Best regards.
> >
> > sishen
> >
>
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How will this work?  Is this like the before_filter for each connection?

I prefer this logic:

begin
   connection.query(xx)
rescue StatementInvalid
   reconnect
end

I suppose the mysql reconnect policy follow this way but i''m not sure,
:)

On Fri, May 16, 2008 at 3:06 PM, Courtenay <court3nay@gmail.com> wrote:
> afaik Rails runs
>  ActiveRecord::Base.verify_active_connections!
>
> before each request.  Is this broken?
>
> On Fri, May 16, 2008 at 12:03 AM, sishen <YeDingding@gmail.com>
wrote:
>
>>
>> Should I submit a patch about this?  Thanks.
>>
>> On May 13, 8:13 pm, sishen <yedingd...@gmail.com> wrote:
>> > Hi.
>> >
>> > Sorry for raise an old issue. I have seen the ticket in trac but
no
>> answers
>> > found.
>> >
>> > My database is mysql and when it''s idle for a long time,
the connection
>> lost
>> > and raise some exception.
>> >
>> > I have read the mysql_adapter.rb and find it hasn''t used
the reconnect
>> > policy which is allowed by the Mysql Binding.
>> >
>> > So why don''t enable this feature?  Is this a design
choice?
>> >
>> > I think if we allow to set "reconnect: true" in the
database.yml, the
>> thing
>> > will be better.
>> >
>> > Maybe i miss something, thanks for your all advice.
>> >
>> > Best regards.
>> >
>> > sishen
>>
>>
>
> >
>
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From what I call, Rails does not lose a connection when a StatementInvalid
error is thrown.

Can you prove this in a test?

Sorry if I misunderstood your original post, it isn''t very clear.

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Sorry. I haven''t described it well. I use AR only in my app.

The default live time of mysql connection is 8 hours. When the connection is
idle for longer than that time, the exception throws.

I think there should be a reconnect policy to auto connect to the server
when connection is lost, especially the mysql binding support that, right?

On Fri, May 16, 2008 at 3:24 PM, Ryan Bigg (Radar)
<radarlistener@gmail.com>
wrote:
> From what I call, Rails does not lose a connection when a StatementInvalid
> error is thrown.
>
> Can you prove this in a test?
>
> Sorry if I misunderstood your original post, it isn''t very clear.
>
>
> >
>
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> I think there should be a reconnect policy to auto connect to the server
> when connection is lost, especially the mysql binding support that, right?
Yeah, rails applications will do this transparently.   We don''t want
to have a solution that only works with mysql when the current one
works for all our supported databases.

-- 
Cheers

Koz

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I actually had 3 different people come up to me at MySQLConf and tell
me their AR connections were dropping like this and not reconnecting.
It might be something you want to check into (though I don''t think
there''s a verifiable way to test it).

I''ll try to find out more information from those guys if I can find
their cards...

--Jeremy

On Fri, May 16, 2008 at 8:15 PM, Michael Koziarski
<michael@koziarski.com> wrote:
>
>> I think there should be a reconnect policy to auto connect to the
server
>> when connection is lost, especially the mysql binding support that,
right?
>
> Yeah, rails applications will do this transparently.   We don''t
want
> to have a solution that only works with mysql when the current one
> works for all our supported databases.
>
> --
> Cheers
>
> Koz
>
> >
>


-- 
http://jeremymcanally.com/
http://entp.com

Read my books:
Ruby in Practice (http://manning.com/mcanally/)
My free Ruby e-book (http://humblelittlerubybook.com/)

Or, my blogs:
http://mrneighborly.com
http://rubyinpractice.com

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The catch is, if someone is running AR in daemonized env. outside
actionpack, they gotta call verify_active_connections! manually.

On Sun, May 18, 2008 at 12:54 AM, Jeremy McAnally
<jeremymcanally@gmail.com> wrote:
>
> I actually had 3 different people come up to me at MySQLConf and tell
> me their AR connections were dropping like this and not reconnecting.
> It might be something you want to check into (though I don''t think
> there''s a verifiable way to test it).
>
> I''ll try to find out more information from those guys if I can
find
> their cards...
>
> --Jeremy
>
> On Fri, May 16, 2008 at 8:15 PM, Michael Koziarski
> <michael@koziarski.com> wrote:
>>
>>> I think there should be a reconnect policy to auto connect to the
server
>>> when connection is lost, especially the mysql binding support that,
right?
>>
>> Yeah, rails applications will do this transparently.   We
don''t want
>> to have a solution that only works with mysql when the current one
>> works for all our supported databases.
>>
>> --
>> Cheers
>>
>> Koz
>>
>> >
>>
>
>
>
> --
> http://jeremymcanally.com/
> http://entp.com
>
> Read my books:
> Ruby in Practice (http://manning.com/mcanally/)
> My free Ruby e-book (http://humblelittlerubybook.com/)
>
> Or, my blogs:
> http://mrneighborly.com
> http://rubyinpractice.com
>
> >
>


-- 
Cheers!
- Pratik
http://m.onkey.org

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AR connections timeout and drop, that''s how it is. Rails fixes this in
a
filter. I believe it''s documented.
That''s why on our tt AIM bot I have to verify connections before each
access
(but you knew that, jeremy :P ).    As lifo says.

On Sat, May 17, 2008 at 4:56 PM, Pratik <pratiknaik@gmail.com> wrote:
>
> The catch is, if someone is running AR in daemonized env. outside
> actionpack, they gotta call verify_active_connections! manually.
>
> On Sun, May 18, 2008 at 12:54 AM, Jeremy McAnally
> <jeremymcanally@gmail.com> wrote:
> >
> > I actually had 3 different people come up to me at MySQLConf and tell
> > me their AR connections were dropping like this and not reconnecting.
> > It might be something you want to check into (though I don''t
think
> > there''s a verifiable way to test it).
> >
> > I''ll try to find out more information from those guys if I
can find
> > their cards...
> >
> > --Jeremy
> >
> > On Fri, May 16, 2008 at 8:15 PM, Michael Koziarski
> > <michael@koziarski.com> wrote:
> >>
> >>> I think there should be a reconnect policy to auto connect to
the
> server
> >>> when connection is lost, especially the mysql binding support
that,
> right?
> >>
> >> Yeah, rails applications will do this transparently.   We
don''t want
> >> to have a solution that only works with mysql when the current one
> >> works for all our supported databases.
> >>
> >> --
> >> Cheers
> >>
> >> Koz
> >>
> >> >
> >>
> >
> >
> >
> > --
> > http://jeremymcanally.com/
> > http://entp.com
> >
> > Read my books:
> > Ruby in Practice (http://manning.com/mcanally/)
> > My free Ruby e-book (http://humblelittlerubybook.com/)
> >
> > Or, my blogs:
> > http://mrneighborly.com
> > http://rubyinpractice.com
> >
> > >
> >
>
>
>
> --
> Cheers!
> - Pratik
> http://m.onkey.org
>
> >
>
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> AR connections timeout and drop, that''s how it is. Rails fixes
this in a
> filter. I believe it''s documented.
> That''s why on our tt AIM bot I have to verify connections before
each access
> (but you knew that, jeremy :P ).    As lifo says.
Having said that, there''s no reason why the adapter *couldn''t*
support
a reconnect option, if it''s in the mysql client lib.  I''d be
happy to
take patches for it.

However I certainly wouldn''t want to roll our own reconnect-on-error
thing, retrying sql statements is a great way to lose friends and
invalidate data.


> On Sat, May 17, 2008 at 4:56 PM, Pratik <pratiknaik@gmail.com> wrote:
>>
>> The catch is, if someone is running AR in daemonized env. outside
>> actionpack, they gotta call verify_active_connections! manually.
>>
>> On Sun, May 18, 2008 at 12:54 AM, Jeremy McAnally
>> <jeremymcanally@gmail.com> wrote:
>> >
>> > I actually had 3 different people come up to me at MySQLConf and
tell
>> > me their AR connections were dropping like this and not
reconnecting.
>> > It might be something you want to check into (though I
don''t think
>> > there''s a verifiable way to test it).
>> >
>> > I''ll try to find out more information from those guys if
I can find
>> > their cards...
>> >
>> > --Jeremy
>> >
>> > On Fri, May 16, 2008 at 8:15 PM, Michael Koziarski
>> > <michael@koziarski.com> wrote:
>> >>
>> >>> I think there should be a reconnect policy to auto connect
to the
>> >>> server
>> >>> when connection is lost, especially the mysql binding
support that,
>> >>> right?
>> >>
>> >> Yeah, rails applications will do this transparently.   We
don''t want
>> >> to have a solution that only works with mysql when the current
one
>> >> works for all our supported databases.
>> >>
>> >> --
>> >> Cheers
>> >>
>> >> Koz
>> >>
>> >> >
>> >>
>> >
>> >
>> >
>> > --
>> > http://jeremymcanally.com/
>> > http://entp.com
>> >
>> > Read my books:
>> > Ruby in Practice (http://manning.com/mcanally/)
>> > My free Ruby e-book (http://humblelittlerubybook.com/)
>> >
>> > Or, my blogs:
>> > http://mrneighborly.com
>> > http://rubyinpractice.com
>> >
>> > >
>> >
>>
>>
>>
>> --
>> Cheers!
>> - Pratik
>> http://m.onkey.org
>>
>>
>
>
> >
>


-- 
Cheers

Koz

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