[ZODB-Dev] avoiding conflicts.

[Steve Alexander]

Terry Kerr wrote:
> 
> The problem I have is that this method can take up to 10 seconds to 
> complete, mainly due to the HTTP communication with the external 
> systems, and during high load periods, this method may be called by 
> several different users every second, thus, write conflicts emerge as 
> the method updates the attributes on the global parent objects.  Zope's 
> way of attempting to resolve the conflict is to re-run the method. This 
> works fine, and the conlfict is evenutally resolved even if after 
> several goes.  The problem however is that because the method is run 
> several times, the information is posted to the external systems as many 
> times which in my case is very very bad!

I'd run a separate long-running process to do your HTTP posting. The 
Zope application communicates with this separate process via a queue, or 
perhaps a queue-like object that knows how to collapse a number of 
pending updates into a single one.

You could implement the communication using files on the filesystem. If 
you do it maildir-style then your queue stays intact between restarts.

--
Steve Alexander