Re: psycopg and gevent with pgbouncer
| От | Raoul Duke |
|---|---|
| Тема | Re: psycopg and gevent with pgbouncer |
| Дата | |
| Msg-id | CAF1_pe_52ss290Yh0Ms4JSM0E-Xn1hXL_mC+Zemy2cuneHJOrA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: psycopg and gevent with pgbouncer (Daniele Varrazzo <daniele.varrazzo@gmail.com>) |
| Список | psycopg |
On Thu, Oct 6, 2011 at 3:53 PM, Daniele Varrazzo <daniele.varrazzo@gmail.com> wrote:
On Thu, Oct 6, 2011 at 12:41 PM, Raoul Duke <knevcher@gmail.com> wrote:Good. Note that you haven't included the mailing list in your reply.
> I use psycopgreen for gevent and psycopg2 and it works fine.
If your problem is solved, let it know to other who may stumble in
your request via google.
I don't understand. How can I do that?
Why do you need the psycopg2 pool if you are using pgbouncer? It
> Is there any way to detect if my application reconnect to db (pgbouncer) on
> each client request? I use psygopg2.pool.SimpleConnectionPool.
shouldn't save you a lot.
I use pooler to limit requests to DB. If decide not use pgbouncer I think pooler is required.
The simple connection pool is not appropriate for concurrent programs:
you should use probably the ThreadedConnectionPool, after checking
that the lock it uses is correctly made green by gevent
On Thu, Oct 6, 2011 at 2:31 PM, Daniele Varrazzo <daniele.varrazzo@gmail.com> wrote:
On Thu, Oct 6, 2011 at 9:54 AM, Marko Kreen <markokr@gmail.com> wrote:
> On Thu, Oct 6, 2011 at 10:45 AM, Raoul Duke <knevcher@gmail.com> wrote:>> 2. I use psycopg simple connection pooler :An async connection it is not usable just after it's been created:
>> pool = SimpleConnectionPool(1, 3, connection_string)
>>
>> if I add async option:
>> pool = SimpleConnectionPool(1, 3, connection_string, async=1)
>>
>> I've got an error, than I can't understand:
>> File "/usr/lib/pymodules/python2.6/sqlalchemy/engine/base.py", line 940,
>> in __create_execution_context
>> self._handle_dbapi_exception(e, kwargs.get('statement', None),
>> kwargs.get('parameters', None), None, None)
>> File "/usr/lib/pymodules/python2.6/sqlalchemy/engine/base.py", line 931,
>> in _handle_dbapi_exception
>> raise exc.DBAPIError.instance(statement, parameters, e,
>> connection_invalidated=is_disconnect)
>> OperationalError: (OperationalError) asynchronous connection attempt
>> underway None [{}]
>>
>> Do I understand that when using the gevent, I have to use async option?
>
> I leave that to psycopg guys to answer.
it's in an half baked state where poll() returns POLL_READ or
POLL_WRITE until the client and the server have completed the
asynchronous login handshake. The protocol must be pushed by the
client as described in
<http://initd.org/psycopg/docs/advanced.html#asynchronous-support>.
The wait loop should be somewhere after the connection creation and
before the usage: I don't know if the libraries you are using allow
that.
Note that if you are using gevent and not twisted you may use the
green mode instead
<http://initd.org/psycopg/docs/advanced.html#support-to-coroutine-libraries>,
that provides you async connections whose behaviour is entirely
equivalent to the blocking one (they block a single greenlet and
schedule the other to go). I suspect you should try them instead of
the raw async mode.
-- Daniele
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