creating the postgres engine with the separate QueuePool, like youre
doing, is a good idea to get a better result here. the
"threadlocal" strategy uses this silly "TLEngine" subclass which is
only trying to do that old "engine.begin()/engine.commit()" thing,
which id rather get rid of, as soon as people tell me they can use
the Transaction object that whole thing is gone. if youre having
weird transactions hanging open types of problems i would suspect
that might be where its happening, as it does try to maintain state
(any chance I can get a fully working test program ?). The regular
ComposedSQLEngine does not maintain any state (the underlying pool of
course does).
anyway your problem using the pool is just the "pool" argument not
being propigated, and also there needed to be an exception raise for
a bad URL, which if you SVN up to changeset 1533 youll get. the
program below illustrates how to connect to postgres with your own pool:
from sqlalchemy import *
import psycopg2
def getconn():
return psycopg2.connect(database='test', user='scott',
password='tiger', host='127.0.0.1')
import sqlalchemy.pool as pool
p = pool.QueuePool(getconn, pool_size=20, max_overflow=40)
e = create_engine('postgres://', pool=p, convert_unicode=True)
c = e.connect()
print c.scalar("select now()", {})
please try it out and let me know how it goes. the QueuePool in
version 0.2 had to change slightly from its design in 0.1 to support
"checkin/checkout" counters, as a result of the new requirement that
people can explicitly call "close()" on a returned ConnectionFairy as
opposed to waiting for __del__() to take care of things
cleanly...other than that it is the same code. The regular
ComposedSQLEngine in turn doesnt have anything to say about those
connections, its totally stateless. anything producing a deadlock is
something i need to know about and be able to reproduce ASAP....thanks.
On May 28, 2006, at 7:24 AM, Valentino Volonghi aka Dialtone wrote:
On Sat, 27 May 2006 20:36:56 -0400, Michael Bayer
<[EMAIL PROTECTED]> wrote:
sure, right here:
http://www.sqlalchemy.org/docs/
dbengine.myt#dbengine_connections_context
just switch on 'create_engine('foo', strategy="threadlocal")' and
youve got identical 0.1 behavior.
Not really since I tried that and it deadlocks inside postgres
because of idle transactions.
def _transact(engine):
"""
return an high level function bind to a particulary
sqlalchemy engine
this function is suitable to use as a decorator
a decorated function returns a Deferred while its body
is running in a separate thread
"""
def _transaction(f):
# _transaction *is* the decorator
def _wrap(*args, **kwargs):
def _1():
conn = engine.contextual_connect()
trans = conn.begin()
try:
r = f(*args, **kwargs)
except:
trans.rollback()
conn.close()
raise
else:
trans.commit()
conn.close()
return r
return threads.deferToThread(_1)
_wrap.__name__ = f.__name__
return _wrap
return _transaction
I thought this would work in threadlocal mode but it doesn't.
Not only that but:
def getconn():
... return psycopg2.connect(database='blabla2',
user='blalbla1', password='blabla')
p = sq.pool.QueuePool(getconn, pool_size=20, max_overflow=40)
sq.create_engine('postgres', pool=p, convert_unicode=True)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/engine/
__init__.py", line 92, in create_engine
return strategy.create(*args, **kwargs)
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/engine/
strategies.py", line 30, in create
module = u.get_module()
AttributeError: 'NoneType' object has no attribute 'get_module'
Seems to be caused by the regexp in url.make_url()
Using 'postgres:///' in create_engine causes...
e.connect()
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/engine/
base.py", line 450, in connect
return Connection(self, **kwargs)
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/engine/
base.py", line 177, in __init__
self.__connection = connection or engine.raw_connection()
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/engine/
base.py", line 473, in raw_connection
return self.connection_provider.get_connection()
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/engine/
default.py", line 34, in get_connection
return self._pool.connect()
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/pool.py",
line 84, in connect
return ConnectionFairy(self).checkout()
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/pool.py",
line 130, in __init__
self.connection = pool.get()
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/pool.py",
line 102, in get
return self.do_get()
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/pool.py",
line 227, in do_get
return self._creator()
File "/Volumes/dati/Sviluppo/sqlalchemy/lib/sqlalchemy/engine/
default.py", line 27, in <lambda>
self._pool = poolclass(lambda: dbapi.connect(*cargs, **cparams),
**kwargs)
psycopg2.OperationalError: FATAL: database "host=" does not exist
To close up, don't take this personally please because sqlalchemy
is anyway wonderful, but as things are currently going with 0.1--
>0.2 migration the pain in the butt is sqlalchemy and not twisted.
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