[Python-Dev] Twisted Isn't Specific (was Re: Trial balloon: microthreads library in stdlib)

[Larry Hastings]

Bob Ippolito wrote:
> There is no single PerfectReactor. There are several use cases where
> you need to wait on >1 different event systems, which guarantees at
> least two OS threads (and two event loops). In general it's nice to
> have a single Python event loop ("the reactor") to act on said threads
> (e.g. something just sitting on a mutex waiting for messages) but
> waiting for IO to occur should *probably* happen on one or more
> ancillary threads -- one per event system (e.g. select, GTK,
> WaitForMultipleEvents, etc.)
Why couldn't PerfectReactor be a reactor for other reactors?  A sort of 
concentrator for these multiple event systems and multiple threads.

You ask to listen to sockets, so it instantiates a singleton 
PerfectReactor which instantiates a select() reactor and listens to it 
directly in a single-threaded manner.  If you then ask to listen to 
Win32 messages, the PerfectReactor instantiates a GetMessage() reactor.  
Then, realizing it has two "event systems", it spawns a thread for each 
child reactor with a listener that serializes the incoming events into 
the PerfectReactor's queue.  Bingo, your application doesn't need to be 
written thread-safe, PerfectReactor is platform-agnostic, and you don't 
have to know in advance all the event types you might ever listen to.

Sorry if this is a dumb question (or if I'm mangling the terminology),


/larry/