[Zope-dev] non-zodb persistent registries

[Tres Seaver]

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Chris Withers wrote:
> Hey Tres,
> 
> Tres Seaver wrote:
>> 2. Move the persistent registry stuff out into another package,
>>    including whatever support is needed to allow for people to migrate
>>    existing persistent references.  Effectively, this moves one "extra"
>>    out to a package, *including* its testing dependencies.
>>
>>   zope.persistentregistry (BIKESHED NAMING ALERT)
>>     depends on:
>>     - zope.configuration
>>     - ZODB3
> 
> I was interested to see this for the reason I gave in the subject line, 
> and it might affect the naming of this package... Might I suggest 
> zope.zodbregistry for this?
> 
> The reason being that, for a long time, I've wanted to see a persistent 
> registry that stored in a rdb rather than zodb.

I don't know what that would look like.  I note that the bfg application
registry is actually picklable, because we don't use any non-inert
actions.  The expected gain in startup time turned out to be negligible,
so we don't worry about trying to do this any more.

> However, I'm a bit stumped at how to implement this and certainly having 
> the zodb-based registry mixed in with the zope.component code confused 
> the hell out of me when I last looked. The one that particularly got me 
> was how, in a multi-process/multi-thread setup such as a wsgi app, you 
> would get other threads'/processes' registries to update themselves when 
> a registry in one thread/process was changed. Any ideas how to do this?

Nope.  I've never given it any thought.

> We do actually have this problem with the text-file based registry, it's 
> just that we accept a restart of the server is needed when that text 
> file changes. A "nice to have" would be an equivalent of apache's reload 
> command.

I don't actually understand the usecase:  changing configure.zcml is a
development activity, not a sysadmin one.

> Is anyone else interested in this kind of stuff?

Theoretically, yes.  Practically, no:  I'd rather keep my startup times
under a second. ;)


Tres.
- --
===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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