Hi Ron. Many thanks for your reply. This is also a long running
document processing challenge, there can be 100's (or even thousands)
of records which is why the time problem. The code it uses in my tool
in the CMF. How is it that you send a signal to the long running
process? Is the long running process cronned to look for a record in
the database or is this starting another server of some type.
What I need is something like what you are suggesting - wakes up when
there is work in the hopper and chugs along until it is done and then
goes to sleep (sort of the way a printing queue works). At the same
time it would be great if it was something that had a small RAM
footprint or ran without consuming any more than X mbs. The other
problem I have with this is that it needs to do work in Zope itself
since the final docs end up as objects. I have just found Chris
Wither's product called Stepper. I am not sure it this is for this type
of situation or more for cronned maintenance. I want to be able to
initiate the process right away but asynchronously from the main zope
threads.
Regards,
David
On Tuesday, September 13, 2005, at 06:05 PM, Ron Bickers wrote:
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.
--
Ron
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