[Zope-dev] thread safety in external methods

[Jim Fulton]

Michel Pelletier wrote:
> 
> Robin Becker wrote:
> >
> > How do I do thread safety inside an External method.
> >
> > I want to access a global singleton as
> >
> > def __ZGA():
> >     if not hasattr(sys.modules['__main__'],'__ZGA'):
> >         #unsafe here...
> >         Z=ZGA_calculator()
> >         # initialise things to do with Z
> >         sys.modules['__main__'].__dict__['__ZGA']=Z
> >     return sys.modules['__main__'].__dict__['__ZGA']
> >
> > the problem is controlling access to sys.modules['__main__'].__dict__['__ZGA']. I can't have a
> > global lock inside my external method as I get a different environment with each call (which is
> > why I need the singleton in the first place).
> >
> > It would be sufficient for my purposes if I could guarantee to get certain code run just once
> > at startup time.
> >
> 
> When Zope starts up it imports all the modules containing external
> methods.

No it doesn't. It imports products at startup. It *loads* external
methods when it needs to.

Jim

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