[Zope] timeout, thread, and external connections

[Warnes, Gregory R]

Hi,

I'm writing a tool similar to MatlabDA for the open-source stat package 'R'.
Since R isn't thread safe and is very stateful, I've written code to start
up, communicate with, and close independent R processes.   This is all
working properly.

Now, I want to the connection to the external process to 'timeout' after a
period of inactivity, so I won't end up with an slowly increasing number of
R processes hanging around not doing anything.  I have code to 'pickle' the
session information and terminate the external R process and to start up a
new process and 'unpickle' the state.  This will let me 'restore' the
connection when a new request comes in.

What I don't have is code to implement the timeout feature.  Is there as
'standard' method for doing this within Zope?

My initial thought is to create a new thread when the connection object is
created.  Its sole purpose will be to sleep for the timeout length, check
whether the connection object has been access during the sleep interval.  If
it has, then it will reset 
reset the counter and go back to sleep.  If there has not been any access,
it will lock the connection object, call the pickle routine, close the
connection, and terminate itself.

Has anyone else implemented something like this?  Are there any 'gotchas' or
problems threading under zope. Are there other, better, strategies?  For
instance, is there a 'callback after interval' function exposed by zope to
remove the need for the new thread?

Thanks,

Greg




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