[reportlab-users] strange problem with reportlab and zope

[John J. Lee]

On Mon, 24 Oct 2005, Tyler Tipton wrote:

> I run a plone/zope website that uses python external methods to call
> reportlab for PDF generation. Seemingly everything runs according to the
> plan, I have a python external method that gathers SQL data and then uses
> reportlab to generate the PDF document, then another python script sets the
> HTTP headers and returns the data to the browser.
>
> The problem I am having is that every once in a while after one user has
> generated a pdf, all users who try to generate one after that time will get
> that users account data instead of their intended data. 9 times out of 10
> the correct data comes through but then one set of data seems to get 'stuck'
> and then that data gets returned regardless of who is logged in until a
> certain amount of reports have been generated and then it goes back to
> working fine.

It's a while since I've done anything with Zope, but this certainly sounds 
to me like a problem caused entirely by some concurrency-related bug -- 
nothing to do with the ReportLab toolkit per se.  Are you using threads? 
The SVN trunk is not intended for threaded use.

A few people here are on vacation at the moment, so perhaps somebody will 
have more detailed suggestions tomorrow.

[...]
> The worst part is that I cannot consistently reproduce this error.. I have
> ran numerous tests and closely analyzed all my logfiles and it seems to
> happen completely randomly.

Welcome to concurrent programming!


John