Re: threading

From	"Frank Millman" <frank@chagford.com>
Subject	Re: threading
Date	2014-04-10 13:10 +0200
References	(7 earlier) <CAPTjJmqwhb8O8vq84mMTv+-Rkc3Ff1AQDXe5cs8Y5gY02kHyNg@mail.gmail.com> <li3lho$vpr$1@ger.gmane.org> <CAPTjJmq2xx_WG2ymCC0NNqisDO=DNnJhneGPiD3DE+xeiy5hjg@mail.gmail.com> <li5nju$opm$1@ger.gmane.org> <CAPTjJmoWaHPZk=DAxbfJ=9ez2aj=4yf2C8WMbRYoF5VgN6Exsw@mail.gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.9131.1397128288.18130.python-list@python.org> (permalink)

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"Chris Angelico" <rosuav@gmail.com> wrote in message 
news:CAPTjJmoWaHPZk=DAxbfJ=9ez2aj=4yf2C8WMbRYoF5VgN6Exsw@mail.gmail.com...
> On Thu, Apr 10, 2014 at 7:17 PM, Frank Millman <frank@chagford.com> wrote:
>> The current version of my program uses HTTP. As I understand it, a client
>> makes a connection and submits a request. The server processes the 
>> request
>> and returns a result. The connection is then closed.
>>
>> In this scenario, does async apply at all? There is no open connection to
>> 'select' or 'poll'. You have to ensure that the request handler does not
>> block the entire process, so that the main loop is ready to accept more
>> connections. But passing the request to a thread for handling seems an
>> effective solution.
>

[...]

Thanks, Chris - I am learning a lot!

I have skipped the first part of your reply, as it seems to refer to the 
client. I am using a web browser as a client, so I don't have to worry about 
programming that.

>
> When you write the server, you effectively have the same principle,
> with one additional feature: a listening socket becomes readable
> whenever someone connects. So you can select() on that socket, just
> like you can with the others, and whenever there's a new connection,
> you add it to the collection and listen for requests on all of them.
> It's basically the same concept; as soon as you can accept a new
> connection, you do so, and then go back to the main loop.
>

This is where it gets interesting. At present I am using cherrypy as a 
server, and I have not checked its internals. However, in the past I have 
dabbled with writing server programs like this -

    while self.running:
        try:
            conn,addr = self.s.accept()
            Session(args=(self, conn)).start()
        except KeyboardInterrupt:
            self.shutdown()

In this scenario, the loop blocks on 'accept'.

You seem to be suggesting that I set the socket to 'non-blocking', use 
select() to determine when a client is trying to connect, and then call 
'accept' on it to create a new connection.

If so, I understand your point. The main loop changes from 'blocking' to 
'non-blocking', which frees it up to perform all kinds of other tasks as 
well. It is no longer just a 'web server', but becomes an 'all-purpose 
server'.

Much food for thought!

Frank

Thread

Re: threading Ben Finney <ben+python@benfinney.id.au> - 2014-04-07 13:05 +1000
  Re: threading Roy Smith <roy@panix.com> - 2014-04-06 23:48 -0400
    Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-07 13:56 +1000
      Re: threading Roy Smith <roy@panix.com> - 2014-04-07 08:26 -0400
        Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-07 22:34 +1000
          Re: threading Roy Smith <roy@panix.com> - 2014-04-07 09:22 -0400
            Re: threading Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-04-07 14:41 +0100
            Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-07 16:49 +0300
              Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-08 00:27 +1000
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-07 17:51 +0300
                Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-08 01:12 +1000
            Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-08 00:24 +1000
      Re: threading Rick Johnson <rantingrickjohnson@gmail.com> - 2014-04-08 18:09 -0700
        Re: threading "Neil D. Cerutti" <neilc@norwich.edu> - 2014-04-09 09:50 -0400
          Re: threading Rick Johnson <rantingrickjohnson@gmail.com> - 2014-04-09 08:51 -0700
            Re: threading MRAB <python@mrabarnett.plus.com> - 2014-04-09 18:47 +0100
              Re: threading Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-04-10 11:35 +1200
                Re: threading Roy Smith <roy@panix.com> - 2014-04-09 19:53 -0400
                Re: threading Andrew Berg <robotsondrugs@gmail.com> - 2014-04-09 19:02 -0500
                Re: threading Steven D'Aprano <steve@pearwood.info> - 2014-04-10 02:43 +0000
                Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 13:08 +1000
                Re: threading Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-04-10 09:23 +0100
                Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 19:11 +1000
            Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 04:00 +1000
            Re: threading Steven D'Aprano <steve@pearwood.info> - 2014-04-10 03:44 +0000
              Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 13:54 +1000
    Re: threading Ben Finney <ben+python@benfinney.id.au> - 2014-04-07 15:22 +1000
    Re: threading Ethan Furman <ethan@stoneleaf.us> - 2014-04-08 11:09 -0700
    Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 21:41 +0200
      Re: threading Grant Edwards <invalid@invalid.invalid> - 2014-04-08 20:30 +0000
        Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-09 00:32 +0200
          Re: threading Rustom Mody <rustompmody@gmail.com> - 2014-04-08 19:17 -0700
  Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-07 08:10 +0300
    Re: threading Paul Rubin <no.email@nospam.invalid> - 2014-04-06 22:39 -0700
      Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-07 08:46 +0300
      Re: threading Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-04-07 19:47 -0400
        Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-08 08:19 +0300
          Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 10:47 +0000
            Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-08 15:10 +0300
              Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 16:37 +0000
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-08 20:17 +0300
            Re: threading Roy Smith <roy@panix.com> - 2014-04-08 09:19 -0400
              Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 15:44 +0000
                Re: threading Paul Rubin <no.email@nospam.invalid> - 2014-04-08 09:38 -0700
                Re: threading Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-04-09 14:42 +0100
          Re: threading "Frank Millman" <frank@chagford.com> - 2014-04-09 15:23 +0200
            Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-09 16:55 +0300
              Re: threading "Frank Millman" <frank@chagford.com> - 2014-04-09 16:46 +0200
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-09 20:31 +0300
                Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 03:52 +1000
                Re: threading Mark H Harris <harrismh777@gmail.com> - 2014-04-10 08:29 -0500
                Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-09 19:20 +0000
          Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-09 23:47 +1000
            Re: threading Roy Smith <roy@panix.com> - 2014-04-09 10:44 -0400
          Re: threading "Frank Millman" <frank@chagford.com> - 2014-04-09 16:30 +0200
            Re: threading Roy Smith <roy@panix.com> - 2014-04-09 10:52 -0400
              Re: threading Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-04-10 11:19 +1200
            Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-09 19:48 +0300
          Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 00:44 +1000
          Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-09 15:29 +0000
          Re: threading Terry Reedy <tjreedy@udel.edu> - 2014-04-09 12:14 -0400
          Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 02:25 +1000
          Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-09 16:32 +0000
          Re: threading Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-04-09 19:44 -0400
          Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 11:05 +1000
          Re: threading "Frank Millman" <frank@chagford.com> - 2014-04-10 11:17 +0200
          Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 19:40 +1000
          Re: threading "Frank Millman" <frank@chagford.com> - 2014-04-10 13:10 +0200
            Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-10 14:43 +0300
              Re: threading Roy Smith <roy@panix.com> - 2014-04-10 08:56 -0400
              Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-10 15:24 +0000
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-10 19:20 +0300
              Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-11 01:32 +1000
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-10 19:25 +0300
                Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-11 03:08 +1000
                Re: threading Rustom Mody <rustompmody@gmail.com> - 2014-04-10 11:14 -0700
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-10 22:44 +0300
                Re: threading Rustom Mody <rustompmody@gmail.com> - 2014-04-10 13:21 -0700
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-10 23:44 +0300
                Re: threading Rustom Mody <rustompmody@gmail.com> - 2014-04-10 22:15 -0700
                Re: threading Rustom Mody <rustompmody@gmail.com> - 2014-04-10 23:50 -0700
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-11 18:36 +0300
                Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-12 01:53 +1000
                Re: threading Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-04-11 16:58 +0100
                Re: threading Rustom Mody <rustompmody@gmail.com> - 2014-04-11 11:54 -0700
                Re: threading Marko Rauhamaa <marko@pacujo.net> - 2014-04-11 22:27 +0300
                Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-11 01:51 +0200
                Re: threading Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-04-11 05:35 +0000
                Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-11 09:26 +0000
                Re: threading Roy Smith <roy@panix.com> - 2014-04-11 08:36 -0400
                Re: threading Grant Edwards <invalid@invalid.invalid> - 2014-04-11 16:18 +0000
                Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-11 02:21 +0200
                Re: threading Terry Reedy <tjreedy@udel.edu> - 2014-04-10 20:23 -0400
          Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-10 21:19 +1000
      Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 02:06 +0000
        Re: threading alister <alister.nospam.ware@ntlworld.com> - 2014-04-08 11:07 +0000
          Re: threading Roy Smith <roy@panix.com> - 2014-04-08 09:13 -0400
            Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-08 23:23 +1000
              Re: threading alister <alister.nospam.ware@ntlworld.com> - 2014-04-08 14:15 +0000
                Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 16:06 +0000
            Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 15:40 +0000
              Re: threading Paul Rubin <no.email@nospam.invalid> - 2014-04-08 09:46 -0700
                Re: threading Chris Angelico <rosuav@gmail.com> - 2014-04-09 02:46 +1000
                Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 17:17 +0000
          Re: threading Sturla Molden <sturla.molden@gmail.com> - 2014-04-08 15:19 +0000

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