Thanks for the fast reply Jeremy,
I will plan to upgrade to Sequel 3.41, I currently have 3.38.
I also like the idea of the connection_validator extension and will try it
now.
So I can just do something like this :
DB = Sequel.connect(DATABASE_URL)
DB.extension(:connection_validator)
.......Other DB stuff....
and it should be good to go?
Regards
IS
On Wednesday, November 7, 2012 7:43:49 PM UTC-8, Jeremy Evans wrote:
>
> On Wednesday, November 7, 2012 6:36:15 PM UTC-8, CaduceusAbode wrote:
>
>> Hi there!
>>
>> I am using Ruby 1.9.3 in my app server that is running on an AWS EC2
>> instance. I have my Postgres DB running on a separate EC2 instance but both
>> instances are in the same security group. When m Ruby code connects to the
>> DB, it uses the Sequel ORM gem ( http://sequel.rubyforge.org/ )
>>
>> Now, I have configured that Postgres 9.1.4 DB to be able to accept
>> connections properly from the app server instance.
>>
>> However, every now and then, I noticed on the app server's logs that it
>> will have trouble connecting to the Postgres DB instance and I would see
>> error messages like these :
>>
>> * PG::Error: could not receive data from server: Connection timed out*
>> or
>> * PG::Error: connection not open*
>>
>>
>> So I went to the Postgres DB instance and looked in
>> /var/log/postgresql/postgresql-9.1-main.log and I see a bunch of messages
>> like these:
>>
>> * 2012-11-07 08:15:17 UTC LOG: could not receive data from client:
>> Connection timed out*
>> * 2012-11-07 08:15:17 UTC LOG: unexpected EOF on client connection*
>>
>> I did searching around the web including stack overflow, and have made
>> sure that my PostgreSQL does not have SSL enabled ( I have "ssl=off" inside
>> my postgresql.conf file )
>>
>> At this point, I am not exactly sure what exactly is the issue in the
>> Postgres configuration. I do not what to mess with the maximum # of
>> connections or maximum timeout values on my production server without a
>> good proven reason.
>>
>> The app server can connect to the DB most of the time, and this problem
>> only shows up intermittently.
>>
>> On the Ruby-side, this is the error trace for "connection not open" when
>> making the Postgres call :
>>
>> PG::Error: connection not open
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:145:in
>>
>> `async_exec'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:145:in
>>
>> `block in execute_query'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/database/logging.rb:33:in
>> `log_yield'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:145:in
>>
>> `execute_query'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:132:in
>>
>> `block in execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:111:in
>>
>> `check_disconnect_errors'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:132:in
>>
>> `execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:372:in
>>
>> `_execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:234:in
>>
>> `block (2 levels) in execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:379:in
>>
>> `check_database_errors'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:234:in
>>
>> `block in execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/database/connecting.rb:229:in
>>
>> `block in synchronize'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/connection_pool/threaded.rb:105:in
>>
>> `hold'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/database/connecting.rb:229:in
>>
>> `synchronize'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:234:in
>>
>> `execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/dataset/actions.rb:744:in
>> `execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:483:in
>>
>> `fetch_rows'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/model/base.rb:785:in
>> `primary_key_lookup'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/model/base.rb:124:in `[]'
>>
>> Similarly, this is the trace for "could not receive data from server" :
>>
>> PG::Error: could not receive data from server: Connection timed
>> out
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:124:in
>>
>> `block'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:124:in
>>
>> `ensure in check_disconnect_errors'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:124:in
>>
>> `check_disconnect_errors'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:132:in
>>
>> `execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:372:in
>>
>> `_execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:234:in
>>
>> `block (2 levels) in execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:379:in
>>
>> `check_database_errors'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:234:in
>>
>> `block in execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/database/connecting.rb:229:in
>>
>> `block in synchronize'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/connection_pool/threaded.rb:105:in
>>
>> `hold'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/database/connecting.rb:229:in
>>
>> `synchronize'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:234:in
>>
>> `execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/dataset/actions.rb:744:in
>> `execute'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/adapters/postgres.rb:483:in
>>
>> `fetch_rows'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/model/base.rb:785:in
>> `primary_key_lookup'
>>
>> /var/lib/gems/1.9.1/gems/sequel-3.38.0/lib/sequel/model/base.rb:124:in `[]'
>>
>> Please let me know what I might have missed, I appreciate it!
>>
>> IS
>>
>
> This is a problem with your connection to the PostgreSQL server, and
> doesn't really have anything to do with Sequel (it's likely you would see
> similar issues with other libraries). If the PostgreSQL server you are
> connecting to is disconnecting the connections because they are idle, you
> can set up a cron job or something similar to make sure the connection is
> used and doesn't time out. Alternatively, if you have control over the
> server, make sure it is not configured to disconnect idle connections
> (though it seems you don't want to mess with those).
>
> If you haven't already done so, you should try upgrading to Sequel 3.41.
>
> Sequel should be disconnecting after it sees one of those disconnect
> errors, and establishing a new connection the next time it needs to execute
> a query, so at most this should only be causing a single error per
> disconnect.
>
> You can also try the new connection_validator extension in Sequel 3.41, it
> may solve your issue transparently (
> http://sequel.rubyforge.org/rdoc-plugins/files/lib/sequel/extensions/connection_validator_rb.html
> ).
>
> Thanks,
> Jeremy
>
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