[Twisted-Python] adbapi / Postgres : LISTEN/NOTIFY and RealDictCursor

Glyph glyph at twistedmatrix.com
Thu Nov 3 22:47:02 EDT 2011

On Nov 3, 2011, at 7:40 PM, Tobias Oberstein wrote:

> Regarding the broader picture: I cannot say I understand what you say completely.
> "maximum file descriptor pollable by select()"
> Is this *nix in general?
> Does that only apply to select.select?

Yep, only to select.select.  Search around for FD_SETSIZE for more information.

> Or also: select.poll(), select.epoll(), select.kqueue() ?

But those may not be available consistently, so you shouldn't hard-code it to use one of those either :).

> How would implementing an IReadDescriptor circumvent the problem? By not using select(), but poll/epoll/kqeue?

It circumvents the problem by allowing whatever mechanism Twisted is using for multiplexing, rather than always using select().  So you still have to select a reactor that actually supports more than  FD_SETSIZE sockets.

> In any case: we're running FreeBSD, so epoll() is out.
> Is there even a kqueue-based Twisted reactor?

Yes... ish.  More detail here: <http://twistedmatrix.com/trac/ticket/1918>.

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