On 10:52 am, [email protected] wrote:
Hello list,
I need to implement a graceful shutdown procedure for a twistd
application.
The application is made up of two services: an internet.TCPClient and
an internet.TCPServer.
They're glued together with a MultiService instance, which is in turn
set
to have 'application' as parent.
The server and the client work together, making a proxy (SMTP server
and
AMQP client).
My goal is the following:
- intercept a SIGTERM signal
- 'block' on the server side: since it's SMTP I get this by setting a
variable that makes the server return tempfails (4xx) for new messages,
while keeping current sessions active
- wait until current requests are satisfied (I keep a dictionary of
current
pending messages)
- shut the whole thing down
This is exactly what before shutdown triggers are for. Alternatively,
use the higher-level API and implement `stopService` on one of your
services.
Either way, return a `Deferred` that only fires when you're satisfied it
is time for shutdown to proceed.
You said before shutdown triggers are too late but you didn't say why.
I think that's based on a misunderstanding - but if not, then explain
why it doesn't work for your scenario.
Jean-Paul
What is the best solution for this use case? It's not really clear to
me
how to catch SIGTERM and handle pending requests *before* the
underlying
services start to shutdown (i.e. even addSystemEventTrigger('before',
'shutdown', callable) is called too late for my needs).
Thank you very much for your help!
Fabio
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