[Twisted-web] Single-threaded WSGIResource
exarkun at twistedmatrix.com
exarkun at twistedmatrix.com
Wed Feb 3 08:21:41 EST 2010
On 07:56 am, cristiano.paris at gmail.com wrote:
>On Tue, Feb 2, 2010 at 11:13 PM, <exarkun at twistedmatrix.com> wrote:
>>...
>>Can you use a thread-local SQLite3 connection, or is that logic buried
>>too deeply in some other code?
>
>It is, so this is not an option.
>>Another option (I think - untested) would be to give WSGIResource a
>>different implementation of the thread pool interface:
>>
>>class NotThreadPool:
>> def callInThread(self, f, *a, **kw):
>> f(*a, **kw)
>
>Well, that would work too but I think it isn't more elegant than my
>solution yet being shorter, as you still have to know how the
>_WSGIRequest's code works.
I disagree. The fact that a threadpool is used is part of the public
interface. The public WSGIResource class accepts a threadpool as an
argument to its initializer. The threadpool interface itself is public.
Basically, this is a parameter you're supposed to be passing in, and
you're supposed to have it configured in a way which is appropriate for
your application.
>
>A better option would be to delegate the threading strategy to
>subclasses of a generic "adapter" class which:
>
>1 - Turns a Twisted Web request to a WSGI environment upon creation
>(i.e. in the __init__ method), adapts the input/output/error streams
>and so on.
>2 - Let the class user start the WSGI application, whatever this means
>(start a thread or passing control straight to 3).
>3 - Calls the WSGI application after starting to get the output from
>it.
>4 - Writes the output the client.
>
>The adapter class provides 1 and 3. Since 2 and 4 deal with the
>threading/non threading strategy, they wouldn't be directly
>implemented by the adapter class: they are implemented in subclasses
>providing the wanted threading strategy.
>
>My two cents.
I'd have a hard time deciding whether this is an improvement without
seeing an actual implementation. I'm not convinced it's necessary for
your use-case, though.
Jean-Paul
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