[Twisted-Python] Need Exception that will stop ther reactor within twistd
Nicolas D. Cesar
ncesar at lunix.com.ar
Thu Nov 30 13:00:28 MST 2006
my apologies for the delayed answer, i've been very busy latelly.
El Martes, 28 de Noviembre de 2006 06:07, glyph at divmod.com escribió:
> >Actually is type 1, but there are horrible (network) conditions were de
> >application should stop.
>
> No, there aren't. What happens when I run your application in-process with
> my webserver? Should the webserver stop simply because your protocol is
> not working?
Well, yes I agree with you: not a webserver. So, I'll shortly describe my
application.
I have multiple LSTP (Linux Terminal Server Project) servers. All servers are
(almost) the same, and any of them can serve any client. There are arround
8-12 servers and 150+ clients. I'm developing a twisted application that
balances clients requests (by filtering DHCP discover/requests packets. (I
attached an image, my application is called multiltsp). I'm using ip_queue
for this.
Each server has a daemon, they syncronize themselves periodically. Every
daemon knows the connection state of the others, and based on that
information they create it's own "valid MACs' list".
There is a LDAP somewhere that has all client MACs that are in the group (eg.
the 150 clients) and from time to time, multiltsp re-reads this list. (I'm
simplifying much of these details). I'll call this list "ALL-MACS"...
[continued below]
> Just don't call reactor.stop at all unless you are writing top-level
> infrastructure code. Your application should have some other, more
> structured way of reporting fatal shut-down errors to its run container
> (e.g. runContainer.applicationEncounteredFatal(xxx)), not simply raising
> exceptions and hoping someone is listening. Unless you give more specifics
> that indicate that your special case is special-er than any other I've seen
> before, I'll stand by this. :)
[continuing with my explanation]
... all multiltsp daemons MUST have the ALL-MACS list identical, in case there
is a out of sync[1] problem the (incorrect) server must quit and the others
must handle the clients.
There are serveral services involved in this application (the multicast UDP
protocol, a shell, the ip_queue reader and others), but a major problem as
stated above MUST get the application down with some special clean up.
Glyph, I hope you understand my rustic English in the explanation above. Any
advice or suggestion please respond this email.
Greetings,
[1] This process involves a unique serial and many timeouts and a
posible "FLUX" state, I just made a simple conclusion so we can argue about
my twistd special need.
--
Nicolás D. César <ncesar at lunix.com.ar>
Lunix S.R.L. -[ http://www.lunix.com.ar ]-
GnuPG Public Key: gpg --keyserver wwwkeys.pgp.net --recv-key 0x3606F3E6
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