[Zope-Coders] Persistent Sessions question

[Evan Simpson]

Chris McDonough wrote:
 > This looks pretty good!  Shane's "external mount" product seems to work
 > for this purpose as well:

I shied away from that, and someone else's MountedStorage product, 
because neither has been updated in a while.  On the other hand...

Shane Hathaway wrote:
> Funny you should ask.  I've just created a product for a customer called 
> DBTab.  It lets you mount databases (including ZEO) using a simple 
> configuration file, similar to /etc/fstab.  Works great so far.

By this, do you mean a file containing a list of storage description and 
mount point entries?  Do they all auto-mount, or do you provide a ZMI 
control interface?  I'd love to see it.

Congratulations on Tanner's birth, by the way!

> It should work, although there's a bug in ZODB/Mount.py: long-running 
> transactions that work on lots of ZODB objects can exhaust all the 
> available mounted connections

Does the "lots of ZODB objects" apply only to the mounted storage, or is 
there danger in long-running transactions that work on many objects in 
the main storage, but only read or twiddle a few objects in the mounted 
storage?

Chris McDonough wrote:
 > It should work fine in theory but I suspect
 > you'll get a magnitude increase in conflict errors over a comparable
 > local storage

This is primarily a risk when sessions are created or destroyed, right? 
  I'm expecting a low volume of session starts/ends and a high volume of 
session changes.

 > FWIW, also, please try to use Zope 2.6 instead of Zope 2.5

Just made the switch, since I advocated it to someone else a few day ago 
:-).  Love that error_log!  Where's the Folder Settings tab that the 
CHANGELOG talks about?

Thanks,

Evan