On Tue September 13 2005 02:52 pm, David Pratt wrote:
> Hi. I have a workflow that is triggered by a file upload and the
> processing of the file can be minutes of processing depending upon the
> size of the file uploaded. I am concerned about number of threads
> available to serve zope so I believe this is a good candidate for an
> asynchronous process. I am looking for some type of outline to do
> this. Currently a tool does the work that is triggered by workflow
> script. My hope is to have this process run and send the user an email
> to advise when the process has completed instead of the user waiting
> for a response or potentially timing out waiting for one. What steps
> could I take to make this an ansynchronous process?
I had to do something like this when processing a lot of data to create PDF
documents to send via email. The time to do so was too long for them to sit
and wait, so I created a separate process to do the job. I don't know if
this is the best way, but it wasn't very difficult and it has been working
without problems for many months.
When a user requests the document, I add a record of needed information to a
MySQL table (the "queue"), send a signal to the long-running process
(described next) and immediately return a thank you page. A
separate-from-Zope long-running Python process waits for a signal, reads the
queue table, does what it needs to do, empties the processed items from the
queue, and goes idle. It can handle things like getting a signal while it's
processing a queue and "catching up" occassionally if it missed a signal
(for whatever reason).
Hope this helps.
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