On Wed, 31 Dec 2008 10:51:38 -0500, Darren Govoni <dar...@ontrenet.com> wrote:
Hi Jean-Paul,
 Thank you for those suggestions. I can post some simple code after I
get further. The psuedo code of what I want to do is like this:
every few seconds, check a message queue (I see how this is done):
  if there is a message, spawn a deferred so I don't block:
        # The deferred should immediately call a method in a separate
        # thread (wisted kind) to process the message
        # Allow for 10 or so deferreds to be processing messages
        # in parallel while the reactor continues to receive them
        # but block scheduling the deferred if the pool is maxed
        # out

A Deferred is just a convenient way to keep track of callbacks.  It's
not an active thing, so to "spawn" one doesn't make much sense.  Instead,
you spawn something else and use a Deferred to keep track of its result.


Sorry if this is lacking in detail, i'm trying to test the idea in a
simple way with twisted first. If I set up a deferred before calling
reactor.run(), then of course, it runs, but after reactor.run() I have
to invoke reactor.callLater(...) so its a bit different, but what I'd
like is something like reactor.callNow(...) that doesn't block and
invokes the generator in a thread pool.

You probably want twisted.internet.threads.deferToThreadPool (or the older
deferToThread).  From its docstring:

 Call the function C{f} using a thread from the given threadpool and return
 the result as a Deferred.

Jean-Paul

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