[Zope] Counter Rentrancy

[Daniel Rusch]

I could be wrong here, but we did something similar, setting proprieties
like this. Although the code is re-entrant what you may see, if you have
high enough traffic rates, is that depending on exactly what you are
doing you may get Conflicting write exceptions. Additionally, you should
be aware that each manage_changeProperties will be logged in your ZODB
(look at the undo list) which means that your ZODB will grow. If you
have high traffic rates it will grow at an unbelievable rate (ours did).
The conflicting write scenario and the writing to the ZODB also means
that you will suffer (maybe minor) performance degradation. Are you
using a database?

Dan
David Kyte wrote:
> 
> Hi,
> 
> If I have a DTML document for generating and tracking say
> order numbers, is the code rentrant/Atomic?
> 
> <dtml-call "REQUEST.set('counter', counter + 1)">
> <dtml-call "manage_changeProperties( counter=REQUEST['counter'] )">
> <dtml-return counter >
> 
> What I'm really asking is how many threads run in parallel, and
> how would multiple threads accessing this code react.
> 
> Do I need some form of transation or locking?
> 
> Thanks in anticipation
> 
> David Kyte
> 
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