Re: WSGI: creating a new tracker instance for each request?

* Christof Meerwald <[email protected]> [20200205 22:00]:
> On Wed, 5 Feb 2020 12:28:32 +0100, Thomas Arendsen Hein wrote:
> > * Christof Meerwald <[email protected]> [20200205 00:08]:
> >> just noticed that in wsgi_handler.py we create a new tracker instance
> >> for each request:
> >> 
> >>   tracker = roundup.instance.open(self.home, not self.debug)
> >> 
> >> is that really intentional/needed? It seems like a significant
> >> performance issue to me.
> > It cost a bit of performance.
> >
> > Some quick measurements:
> > echo -e 'help'|roundup-admin -i . -> 0.280s
> > echo -e 'display user1'|roundup-admin -i . -> 0.502s
> > echo -e 'display user1\ndisplay user2'|roundup-admin -i . -> 0.505s
> >
> > So I'd say about 0.2 seconds on our roundup server, which is a VM on
> > a slightly old hardware.
> 
> Yes, 0.2 seconds for each request (even if it's just a static .css
> file), seems significant to me.

It is significant, but you should really consider serving static
files directly from a generic web server.

I have something like this in the apache config for every tracker:

  Alias /test/@@file/ /srv/roundup/test/html/

> Anyway, I think at the moment I would only allow easier customization,
> something like
> 
> https://bitbucket.org/cmeerw/roundup/commits/4f6d7744edd03c4abbcc7b8e890761a1fd25b4d8
> 
> so the behaviour can easily be overridden, probably with something
> like this to reuse tracker instances:
> 
>     @contextmanager
>     def get_tracker(self):
>         try:
>             tracker = self._pool.pop()
>         except IndexError:
>             tracker = roundup.instance.open(self.home, not self.debug)
> 
>         yield tracker
> 
>         self._pool.append(tracker)
> 
> 
> > The only problem that I see is that with database backends that
> > allow concurrent access without a global lock, commits of a tracker
> > state may happen too early.
> 
> I am confused - is that related to the above?

Yes, it is. I thought that you wanted to use a single/global tracker
instance, not a pool of tracker instances that are reused after a
request has finished.

With a pool everything should be fine.

Regards,

Thomas

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Thomas Arendsen Hein <[email protected]>
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