[Zope-dev] ERROR(200) ZODB Couldn't load state for... Memory problem?

[Chris McDonough]

On Fri, 2004-07-23 at 16:21, Tim Peters wrote:
> [Chris McDonough]
> > ...
> >          self._f[current] = open(self._p[current],'w+b')
> > 
> > .... will be likely to fail at the last line if you're using
> > nonpersistent cache files, because self._p[current] is (bogus)
> > '1-None-0' (relative bogus filename).
> 
> Is it really *likely* to fail? 

I suppose it depends on the working directory of the shell/process used
to start Zope.  Zope doesn't mess with the working directory on its own,
AFAIK.

If you follow Richard Stevens' ("UNIX Network Programming" guy,
apparently now dead) advice, he says that "well-behaved" daemon
processes should change their working directory to "/".  So I suspect
there are daemonizers that do this.

Guido's zdrun daemon (which "zopectl" uses) gives you an option to set
the working directory of the daemonized process, but I don't use it
(neither zdrun nor the option, that is).  It does nothing to the working
directory by default.

But I think the common case is that the program is run out of an
/etc/init.d "rc" script, and I suspect the working directory is "/" when
Zope gets started in that circumstance.  Which I guess makes the error
understandable.

> It's just a name, and it's opened in
> 'w' ('+b') mode, not 'r' mode.  That is, it creates the file -- no
> file of that name need already exist (and if one does, it tries to
> overrwrite it).  Running on Windows most days, I'm not usually aware
> of all the permission bugs Linuxheads delight in torturing themselves
> with <wink>.

Yes.  Gotta agree with you there.  I don't think a day passes where I
don't want to rip the face off the guy who proclaimed that TCP ports
below 1024 couldn't be bound to by a user other than root.  What a
disaster.

> > There should probably be a _using_persistent_cache flag attr rather than
> > trying to inspect self._p to find out if we're using persistent caches.
> 
> +1.  As you later discovered, this "hmm, let's try to guess what we're
> doing based on obscure droppings" business is a continuing bug
> factory.

Thankfully, Dieter fixed it so it doesn't (at least in this one case).

> 
> > I may try to work up a patch + test for this later.
> 
> I'm neutral on whether you try, but +1 on you actually doing it <wink>.

Too late!  It's already fixed.  I didn't know either. ;-)  This thread
was full of sound and fury....

- C