gl...@divmod.com wrote:
On 04:19 am, luper.ro...@gmail.com wrote:
My first attempt was to run the reactor in the main thread, but the
application was "freezing" when e.g. doing a SELECT with
SQLAlchemy/psycopg2 (I guess because psycopg2 just waits for data and
blocks the twisted reactor). So I put reactor.run() in a thread and it
works, but I'm getting strange issues on some platforms (for example I
can't connect at all on *some* OSX computers, getting a "reactor
stopping" log from twisted without any further error), and I feel I'm
doing the whole thing terribly wrong.
These errors sound like you are making Twisted API calls from threads
other than the reactor thread by accident. There's no obvious fix
except for "don't do that" :).
Yes, I did not pay attention to separate Twisted from the main thread at
all, apart from putting reactor.run() in another thread.
My suggestion would be to move the SQLAlchemy/psycopg2 into threads,
with e.g. deferToThread, rather than putting the reactor into a thread.
Then the reactor won't freeze while the blocking SQL stuff happens.
So my question is, how to do proper SSH port forwarding with conch in
an application that also uses the tunnels not the asynchronous way ?
If running the reactor in a thread is OK, are there particular things
to watch out for ?
There's no reason that running the reactor in a thread shouldn't work;
it's just generally tricky (especially if you're working with an
existing codebase) to completely avoid calling Twisted APIs from other
threads.
This implies too much modifications in my code, I think I will put the
whole Twisted stuff in a separate process and interact with it via
simple IPC, as I don't use that much of Twisted in the GUI code anyway.
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