On Sep 6, 2008, at 5:07 PM, gatto wrote:
>
> global phase
>
> try:
> if phase == 'start':
> phase = 'running'
> except:
> phase = 'start'
>
> if phase == 'start':
> self.engine = create_engine('mysql://' + app_config.database.user +
> ':' + app_config.database.password + '@' + app_config.database.host +
> ':3306/' + app_config.database.schema)
> metadata.bind = self.engine
> metadata.bind.recycle = 3600
this greatly complicates what needs to be done. heres a pseudo
mod_python application. "module level" means, "not inside of a def
which is called within the request".
import sqlalchemy as sa
import sqlalchemy.orm as orm
engine = sa.create_engine(<url>)
meta = sa.MetaData(engine)
# define tables
# define classes
Session = orm.scoped_session(orm.sessionmaker(bind=engine))
from mod_python import apache
def handler(req):
ret = Session.query(SomeClass).filter(..).all()
req.write("Number of objects: " + len(ret))
return apache.OK
in the real world, the things above regarding engine, metadata, etc.
would be in a different python source file, which you would invoke
using "import mymodule" at the same level.
> i also have one other concern.. in periods of high traffic, the
> number of apache processes might outpace the number of mysql
> max_connections i configured (300 at the moment).
300 connections is unbelievably high, and would many hundreds of megs
of memory on both client and server. Unless you're eBay, it should
hardly be possible to ever use more than 20 or 30 simultaneous
connections across your entire application. If your mod_python is
using a forked process model, then in fach each connection pool will
only use one connection since there is only one request handled per
process, in which case the maximum child forks you've configured would
determine the actual number of connections opened.
> right now. but i'm looking toward the future... perhaps there isn't
> much i can do about that until i move on to connection pooling?
the SQLA engine always pools connections.
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