[Dancer-users] Dancer and EV/thread-based servers

Nick Knutov mail at knutov.com
Wed Jan 25 11:47:16 CET 2012

+ How to change (if needed) all initialization in the app.pm, which are 
not in `before hook`, example:

#env perl
use ...;

# this is calling at startup of the script

# and later hook before, get, etc
get '/' => sub {...};

25.01.2012 16:39, Nick Knutov пишет:
> I'm new to it, and I always worked with preforked scripts (like FastCGI
> or Starman). Now I want to process several requests at the same time
> with one app process (without [pre]forking), with servers like Coro
> (green threads, I think) or Feersum (EV). Is it possible?
> And the main question about compatibility, I think, is how to declare
> global variables, which are local to current handled request (because I
> don't know how are they shared inside one process between threads/etc).
> For example, I have hashref $data, some functions in my modules (or my
> Dancer' plugins) generates $data->{fields} and it passes to template()
> at the end of route execution. $data now is `our $data` in app.pm. The
> same with DBI connections. Is it ok or should I change it in some way?
> 25.01.2012 15:57, Pedro Melo пишет:
>> Hi,
>> On Tue, Jan 24, 2012 at 10:27 PM, Nick Knutov<mail at knutov.com> wrote:
>>> the question may be not about Dancer itself, but what should I know
>>> to write
>>> Dancer' plugins and applications compatible with EV- and threads-based
>>> servers?
>> I regularly use Dancer with EV-based servers (Twiggy using the EV
>> backend to AnyEvent and Feersum), I don't have any problems, but maybe
>> I'm missing what you mean by "compatible".
>> If you are asking if the plugins can use the EV capabilities during a
>> single request to start several calls to external network services,
>> collect responses and generate the result, the answer is yes. See the
>> metacpan web app for an example using Catalyst that should be
>> applicable to Dancer with little modification.
>> But if you're are looking for a way to process several requests at the
>> same time, for example processing a second request while the first is
>> waiting on some network protocol, then the answer is no, at least for
>> Dancer v1, don't know Dancer v2 yet. AFAIK, only Tatsumaki will allow
>> you to multiplex multiple HTTP requests on the same process.
>> But between Dancer requests, when the control returns to the EV core,
>> you can run other callbacks. So you can, for example, have a XMPP bot
>> (using AnyEvent::XMPP2) running in the same process as a Dancer app,
>> and interact with it, even to query Dancer internals and/or modify
>> configurations. The XMPP processing will occur between Dancer
>> requests.
>> You can also use AnyEvent timers with a Dancer app. Again, they will
>> be triggered between requests. Useful to collect stats on a Dancer app
>> and send them to a remote server.
>> I use those last two quite a lot actually.
>> Bye,

Best Regards,
Nick Knutov
ICQ: 272873706
Voice: +7-904-84-23-130

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