[Zope] Re: ZEO-Client

[Tres Seaver]

Arenz, Ralph wrote:
> 
> -----Ursprüngliche Nachricht-----
> Von: Tino Wildenhain [mailto:tino at wildenhain.de]
> Gesendet: Mittwoch, 12. Januar 2005 13:47
> An: Arenz, Ralph
> Cc: 'zope at zope.org'
> Betreff: RE: [Zope] ZEO-Client
> 
> 
> On Wed, 2005-01-12 at 11:42 +0100, Arenz, Ralph wrote:
> 
>>-----Ursprüngliche Nachricht-----
>>Von: Tino Wildenhain [mailto:tino at wildenhain.de]
>>Gesendet: Mittwoch, 12. Januar 2005 11:34
>>An: Arenz, Ralph
>>Cc: 'zope at zope.org'
>>Betreff: Re: [Zope] ZEO-Client
>>
>>
>>On Wed, 2005-01-12 at 11:16 +0100, Arenz, Ralph wrote:
>>
>>>Hi,
>>>
>>>i' am using Zope-2.7.3 and i wan't my client-storages to be connected at
>>>zope-startup.
>>>In Zope-2.6.3 i used "open_at_startup" in DBTab but this option seems
> 
> not
> 
>>to
>>
>>>be included
>>>in release 2.7.3, however i can't find it in component.xml. If i add it
> 
> to
> 
>>>zope.conf anyway i get
>>>an exception.
>>
>>>What do you mean by "open_at_startup"?
>>>If you configured the storages in zope.conf,
>>>you go to ZMI and add a DBTab Mount point,
>>>check all storages you want to mount 
>>>and add. From now on the clients are connected
>>>each time zope starts.
>>
>>>HTH
>>>Tino
>>
>>
>>The option "open_at_startup" means that the client-databases are opened at
> 
> 
>>zope-initialization (not when zope is already up). If this fails zope
> 
> won't
> 
>>come up.  
>>That feature is useful if Zope shouldn't run without an paticular storage.
> 
> 
>>This works the same if you do it like I described. Once you use the
>>database, it is required for zope to start up. e.g. Zope will wait
> 
> 
> when does it wait, is the question!
> 
> 
>>until the database (zeo) is ready.
>>Regards
>>Tino
> 
> 
> If i using the option "open_at_startup" my stupid-log under 2.6.3 shows
> "client-connected" before ZServer is up on it's desired port. Without this
> option the connection
> takes place after ZServer is up on it's port, that the significant
> difference. 
> 
> Sometimes there is a time delay of a few minutes after zope is up before the
> connection
> is made (the mounted storage is about 6GB ;-)). I can't except these delay
> so i packed this into the initialization part (before zope is up) with the
> option "open_at_startup". 
> 
> So back to my first question, where ist that option gone in Zope-2.7.3?
> 
> any ideas?

Zope 2.7 binds the server ports much earlier in the startup process than 
it used to.  The current version of the option is the 'wait' key of the 
'zeo-client' section of zope.conf;  it causes the database / storage 
intialization to block while establishing the connection and verifying 
the cache, but the intialization itself starts *after* binding the 
server ports.

A minutes-long startup is likely due to the client's need to verify a 
large persistent disk cache;  one workaround would be to turn off 
persistent caches;  a longer-term solution would be to work with the 
folks on zodb-dev to land a set of improvements to the cache 
verification code (they live on a branch somewhere, I think).

Tres.
-- 
===============================================================
Tres Seaver                                tseaver at zope.com
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