Threads vs subprocesses

[John O'Hagan]

On Sat, 16 Jun 2012 13:27:45 -0400
Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:

> On Sat, 16 Jun 2012 20:01:12 +1000, John O'Hagan
> <research at johnohagan.com> declaimed the following in
> gmane.comp.python.general:
> 
> > 
> > That looks like a possible way to do all the streams in a single thread,
> > although it works a little differently from your outline above if I
> > understand you correctly, in that only the events know their start times
> > and they are produced by iterators which can be modified on the fly and
> > which can be added and removed from the overall process at any time, so
> > it's not possible to know in advance which iterator will produce the
> > chronologically next event. I think
> 
> 	Which is why I mentioned processing all events at a time-point, then
> iterate for the next events if any are generated -- and a "time-ordered"
> (aka; priority) list, so the new events are positioned in the correct
> sequence against any other events that are in it.
 
Now I get it, I thought you meant generating all events ahead of time.

> > that means that any ordered list of events would have to be re-ordered after
> > each event is read. It might be worth a try though. I notice there is simpy
> > for
> 
> 	Not "after each event is read" but when a new event is
> generated/inserted. The list is not a FIFO where new events are added to
> the end, but more of a priority queue where the lowest time is the next
> to be retrieved.

You're right, of course.

> > discrete event simulation in python. I'll look into it, thanks.
> >
> 	One major difference is that traditional discrete event simulation
> uses a false clock -- the simulation time advances to the next (first
> pending) event time immediately. You'd need to modify that operation to
> put in a real-time clock "sleep until" effect.

My events are already handled that way so that's easy - the hard part is the
more complex logic required by doing it without threads. Or maybe it's just
different, I'm in the process of getting my head around it; thanks for the
pointers.

John