[Zope-dev] Zope woes continue

[Tres Seaver]

Michel Pelletier <michel@digicool.com> wrote:
> 
> > -----Original Message-----
> > From: Stuart 'Zen' Bishop [mailto:zen@cs.rmit.edu.au]
> > Sent: Wednesday, December 08, 1999 8:58 PM
> > To: Michel Pelletier
> > Cc: zope-dev@zope.org
> > Subject: RE: [Zope] Zope woes continue - server going down regularly.
> > (pos sible solution)
> >
> >
> > On Wed, 8 Dec 1999, Michel Pelletier wrote:
> >
> > > This is because the connection gets opened, but never
> > closed.  Zope 2.x
> > > is hardwired to have only 7 available database connections.  We'll
> > > probably add a knob in 2.2 that lets you configure the number of db
> > > connections.  In either case, the problem is not the hardwiring, the
> > > problem is that your code has a bug in it, because you do
> > not free the
> > > resource you are consuming.  Do an:
> > >
> > >   x.close()
> > >
> > > at the end of your method and you won't run out of connections.
> >
> > Erm.... shouldn't ZApplicationWrapper have a __del__ method
> > to do this,
> > just in case? It isn't in there...
> 
> I messed up, it's x._p_jar to get the connection, but I see your point.
> You wouldn't want to do this, because other objects other than the root
> object may be using it.

Who has access to the newly-created connection, beyond the ZApplicationWrapper
object which is going to go out of scope and be destroyed?

> 
> > Otherwise, you would really need
> >
> >     try:
> >       x = Zope.app()
> >       # ... stuff
> >       return "Hello World!"
> >     finally:
> >       x.close()
> 
> Yes this actually works best.
> 
> -Michel

I don't buy it:  if Zope.app() constructs and returns an object, whose
constructor has a side effect of opening a new ZODB connection, then that object
OWNS that connection and should clean it up in its destructor.  

Using try..finally to handle a _hidden_ side effect is convoluted -- this is why
refcounts were invented.

Tres.
-- 
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Tres Seaver         tseaver@palladion.com    713-523-6582
Palladion Software  http://www.palladion.com