[racket] Web server

That sounds like a similar technique to node's cluster module (ignoring the
very different languages and server implementations ie async io v threads)
On 17 Jul 2014 15:50, "Brian Adkins" <racketusers at lojic.com> wrote:

> [forgot *again* to reply-all and only sent this to Jay initially -
> resending to group]
>
> Thanks for the response Jay.
>
> I may have glossed over the parallelism & concurrency aspects a bit too
> much when I first read those sections in the Racket Guide. I now see in
> 20.1 re: Futures:
>
> "The level of parallelism available from those constructs, however, is
> limited by several factors, and the current implementation is best suited
> to numerical tasks."
>
> and in 20.2:
>
> "The place form creates a place, which is effectively a new Racket
> instance that can run in parallel to other places, including the initial
> place."
>
> "Places" appears to be similar to my current approach of having multiple
> Ruby/Rails processes handle web requests. In the case of Ruby/Rails, it's a
> very inefficient use of memory, i.e. the amount of RAM needed to fully
> utilize all cores is *much* higher than it should be when spinning up
> multiple app server processes that each load the entire Rails framework.
> Each Rails process is essentially single-threaded.
>
> I was hoping to gain a big improvement of Ruby/Rails with Racket, and that
> may be possible even with the current implementation (both Ruby & Rails are
> performance-challenged), but can you give me some idea of the level
> importance multi-core performance is in the Racket community moving
> forward? I'm taking a fairly long term perspective with Racket, so the
> "roadmap" is as important to me as the current implementation.
>
> I'm referring to Racket in general, not just the web server.
>
> I haven't done much research or testing yet, so maybe a combination of
> Places and Threads will be sufficient for my needs. Maybe one Place per CPU
> core w/ multiple threads to keep the CPU busy while some threads are
> blocked on I/O requests.
>
> Thanks,
> Brian
>
> On Jul 16, 2014, at 10:17 PM, Jay McCarthy wrote:
>
> > It wouldn't have a big impact on the server. The big question is how
> > to effectively use multi-core in Racket programs generally.
> >
> > Futures are really only good for numerical codes that stay in the JIT,
> > which doesn't sound like most Web programs. That said, it is trivial
> > to implement:
> >
> > #lang racket/base
> > (require racket/future
> >        web-server/servlet-env
> >        web-server/http)
> >
> > (define (fib n)
> > (if (< n 2)
> >   1
> >   (+ (fib (- n 1))
> >      (fib (- n 2)))))
> >
> > (define (start req)
> > (touch
> >  (future
> >   (λ ()
> >     (response/xexpr
> >      `(html
> >        (body
> >         (p "It's "
> >            ,(number->string
> >              (fib (random 20)))))))))))
> >
> > (serve/servlet start)
> >
> > Boom! That's a servlet that uses multi-core to handle every request...
> > of course, it probably doesn't pay in this or most other programs.
> >
> > Places are for more coarse-grained things and you can pass file
> > descriptors, so it's feasible to have a TCP accepter that feeds work
> > to a group of places servicing the requests. However, places must not
> > use mutation to communicate higher-order values (they can communicate
> > flat values like numbers with mutation), so they couldn't share
> > continuations. It would be trivial to use serializable continuations
> > or to implement a continuation manager that stored all the
> > continuations in a single place. Session affinity doesn't really make
> > a lot of sense in the continuation context, fwiw.
> >
> > My guess is that you could spend less than 100 lines to implement the
> > continuation manager and the place-based worker setup. (This is based
> > on the normal server setup just being 127 lines and the manager
> > interface being implemented in as little as 40 lines.) This might be
> > worth it.
> >
> > Jay
> >
> >
> > On Wed, Jul 16, 2014 at 4:09 PM, Brian Adkins <racketusers at lojic.com>
> wrote:
> >> I haven't looked into the Racket web server much yet, so I'd like to
> understand the implications of this.
> >>
> >> My experience is with stateless http app servers (primarily with
> Unicorn Ruby servers at the moment), so firing up a number of worker
> processes and having something like nginx proxy to them works well to fully
> utilize all cores.
> >>
> >> I think I read that the Racket web server makes use of continuations,
> so I expect some sort of process affinity would be necessary, where a given
> user's requests are always proxied to the same worker process - is that
> right? Is it common to use multiple web server processes in Racket web apps?
> >>
> >> In your estimation, what is the feasibility of adding multi-core
> support to the Racket web server? For example, is it reasonably feasible
> and on the current roadmap, or would it require massive changes to the web
> server?
> >>
> >> Thanks,
> >> Brian
> >>
> >> On Jul 16, 2014, at 8:42 AM, Jay McCarthy wrote:
> >>
> >>> It does not use multiple cores if they are available.
> >>>
> >>> Jay
> >>>
> >>> On Wed, Jul 16, 2014 at 7:02 AM, Sean Kemplay <sean.kemplay at gmail.com>
> wrote:
> >>>> Hello,
> >>>>
> >>>> I am interested in the racket web server for some micro services. Just
> >>>> wondering if by default it runs across multiple cores or if it is
> restricted
> >>>> to one due to threads in racket.
> >>>>
> >>>> Regards,
> >>>> Sean
> >>>>
> >>>>
> >>>> ____________________
> >>>> Racket Users list:
> >>>> http://lists.racket-lang.org/users
> >>>>
> >>>
> >>>
> >>>
> >>> --
> >>> Jay McCarthy
> >>> http://jeapostrophe.github.io
> >>>
> >>>         "Wherefore, be not weary in well-doing,
> >>>    for ye are laying the foundation of a great work.
> >>> And out of small things proceedeth that which is great."
> >>>                        - D&C 64:33
> >>> ____________________
> >>> Racket Users list:
> >>> http://lists.racket-lang.org/users
> >>
> >
> >
> >
> > --
> > Jay McCarthy
> > http://jeapostrophe.github.io
> >
> >          "Wherefore, be not weary in well-doing,
> >     for ye are laying the foundation of a great work.
> > And out of small things proceedeth that which is great."
> >                         - D&C 64:33
>
>
> ____________________
>   Racket Users list:
>   http://lists.racket-lang.org/users
>
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