On 06:08 am, jacopo.pe...@gmail.com wrote:
I am diving into Twisted and Perspective Broker (PB) in particular and I would like to understand more about what happens behind the curtains. Say I have a client and a server on two different machines, the server gets callRemote() 19s in an asynchronous way, these requests are parked in a queue and then served sequentially (not in parallel 13 correct me if I am wrong).
Since, as you point out below, there is only one thread, the remote methods can only be invoked one at a time.
However, rather central to the asynchronous operation of Twisted libraries and applications, the remote method itself may return before the remote call has been completely serviced. So while only one remote method will run at a time, each of the two remote calls may run concurrently at some point before they are responded to.
If everything is implemented in a single thread, how is it possible that while the processor is engaged in the processing triggered by callRemote() 19s at the same time the reactor is ready to listen/accept new events and put them in a queue? To me it looks like there should be at least 2 processes, one for the reactor and on for the rest.
It isn't possible. While the remote methods are running, other events are not being serviced. This is what is meant when people describe Twisted as a "*cooperative* multitasking" system. Event handlers (such as remote methods) run for a short enough period of time that it doesn't matter that the reactor is prevented from accepting new connections (or what have you) for the duration of their execution.
Jean-Paul -- http://mail.python.org/mailman/listinfo/python-list
