[Zope] How to create an ansynchronous method

[David Pratt]

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? Also wanted to 
confirm whether an asynchronous process would free the thread and how 
one can determine whether a thread has been released. Many thanks.

Regards,
David