Re: Why can't I understand what coroutines are?

From	"Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com>
Newsgroups	comp.lang.c++
Subject	Re: Why can't I understand what coroutines are?
Date	2019-08-04 13:58 -0700
Organization	Aioe.org NNTP Server
Message-ID	<qi7gt6$ct1$1@gioia.aioe.org> (permalink)
References	(2 earlier) <cone.1564925032.455203.25830.1004@monster.email-scan.com> <20190804143647.511134ccbc3ef6771a692cf7@cvine--nospam--.freeserve.co.uk> <cone.1564929062.699026.27147.1004@monster.email-scan.com> <20190804164254.8072d620ed92d63e3d8c9d42@cvine--nospam--.freeserve.co.uk> <cone.1564951432.763732.27147.1004@monster.email-scan.com>

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On 8/4/2019 1:43 PM, Sam wrote:
> Chris Vine writes:
> 
>>
>> You have it wrong.
>>
>> For toy programs or for cases where there are only a few concurrent i/o
>> operations running at any one time then native threads are fine.  But
>> using native OS threads with blocking i/o on i/o-bound workloads does
>> not scale.
> 
> Says who?
> 
>>            No one writes a server these days with one thread per
>> connection, which would be required for your blocking i/o: instead you
>> multiplex connections with poll/epoll/kqueue and tune the number of
>> threads to the workload and the number of cores available.
> 
> Maybe you just don't know many people who write server code.

I remember using IOCP back on WinNT 4. The idea of a thread per 
connection simply does not scale. However, creating a thread or two per 
CPU, and using a queue, like IOCP can scale.


> 
>> You can have
>> millions of C++20-style stackless coroutines running at any one time
>> on a thread, although you are going to run out of file descriptors
>> before any such limit is reached
> 
> Sure, and since coroutines introduce an additional level of complexity – 
> something also needs to be aware and keep track of which coroutine has 
> something that needs to be done, instead of efficiently encapsulating 
> all I/O handling logic in a simple, straightforward, execution thread; 
> and no other part of the code needs to give a shit – it still unclear 
> what problem they're trying to solve.
> 
> Modern operating systems have no problems scaling to thousands, and 
> maybe even tens of thousands of execution threads. Perhaps you don't 
> have much exposure to them, and are only exposed to technically flawed 
> operating system, with utterly crappy thread implementations?
> 
>> > > If you use native OS threads for i/o bound workloads, you are 
>> doing it
>> > > wrong.
>> >
>> > Nope. One only needs to understand that I/O bound workloads is not 
>> the only
>> > reason that threads exist.
>>
>> Clueless.
> 
> As opposed to someone who religiously believes that the only reason one 
> someone would use threads is in CPU-bound code?
> 
> Maybe you should talk to Chrome and Firefox folks, and teach them how to 
> write code, since you know so much about it, and explain how stupid they 
> are, creating dozens of threads even when most of their load is I/O bound.
>

Thread

Why can't I understand what coroutines are? Juha Nieminen <nospam@thanks.invalid> - 2019-08-04 09:37 +0000
  Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-04 02:58 -0700
    Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-04 09:18 -0400
      Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-04 11:15 -0700
  Re: Why can't I understand what coroutines are? Louis Krupp <lkrupp@nospam.pssw.com.invalid> - 2019-08-04 04:58 -0600
    Re: Why can't I understand what coroutines are? Juha Nieminen <nospam@thanks.invalid> - 2019-08-05 08:31 +0000
      Re: Why can't I understand what coroutines are? Martijn van Buul <pino@dohd.org> - 2019-08-05 09:51 +0000
        Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-05 14:44 -0700
  Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-04 14:08 +0100
    Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-04 09:23 -0400
      Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-04 14:36 +0100
        Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-04 10:31 -0400
          Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-04 16:42 +0100
            Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-04 16:43 -0400
              Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-04 13:58 -0700
                Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-04 17:36 -0400
                Re: Why can't I understand what coroutines are? Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-08-04 22:43 +0100
                Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-04 22:52 +0100
                Re: Why can't I understand what coroutines are? Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-08-04 23:10 +0100
                Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-04 21:32 -0400
                Re: Why can't I understand what coroutines are? Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-08-05 18:32 +0100
                Re: Why can't I understand what coroutines are? scott@slp53.sl.home (Scott Lurndal) - 2019-08-05 17:48 +0000
                Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-05 20:14 -0400
                Re: Why can't I understand what coroutines are? leigh.v.johnston@googlemail.com - 2019-08-06 04:13 -0700
                Re: Why can't I understand what coroutines are? leigh.v.johnston@googlemail.com - 2019-08-06 04:23 -0700
                Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-06 22:19 +0100
                Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-06 15:19 -0700
                Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-07 00:01 +0100
                Re: Why can't I understand what coroutines are? scott@slp53.sl.home (Scott Lurndal) - 2019-08-06 23:52 +0000
                Re: Why can't I understand what coroutines are? Öö Tiib <ootiib@hot.ee> - 2019-08-06 16:57 -0700
                Re: Why can't I understand what coroutines are? scott@slp53.sl.home (Scott Lurndal) - 2019-08-07 14:41 +0000
                Re: Why can't I understand what coroutines are? Öö Tiib <ootiib@hot.ee> - 2019-08-08 07:10 -0700
                Re: Why can't I understand what coroutines are? scott@slp53.sl.home (Scott Lurndal) - 2019-08-06 23:49 +0000
                Re: Why can't I understand what coroutines are? Robert Wessel <robertwessel2@yahoo.com> - 2019-08-04 22:04 -0500
                Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-04 20:10 -0700
        Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-04 11:20 -0700
          Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-04 20:30 +0100
            Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-04 14:03 -0700
            Re: Why can't I understand what coroutines are? Paavo Helde <myfirstname@osa.pri.ee> - 2019-08-05 09:36 +0300
              Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-05 14:34 -0700
        Re: Why can't I understand what coroutines are? scott@slp53.sl.home (Scott Lurndal) - 2019-08-04 19:46 +0000
      Re: Why can't I understand what coroutines are? Juha Nieminen <nospam@thanks.invalid> - 2019-08-05 08:37 +0000
        Re: Why can't I understand what coroutines are? David Brown <david.brown@hesbynett.no> - 2019-08-05 12:06 +0200
          Re: Why can't I understand what coroutines are? Juha Nieminen <nospam@thanks.invalid> - 2019-08-05 12:20 +0000
            Re: Why can't I understand what coroutines are? David Brown <david.brown@hesbynett.no> - 2019-08-06 15:06 +0200
              Re: Why can't I understand what coroutines are? David Brown <david.brown@hesbynett.no> - 2019-08-06 15:18 +0200
          Re: Why can't I understand what coroutines are? Bonita Montero <Bonita.Montero@gmail.com> - 2019-08-06 13:58 +0200
  Re: Why can't I understand what coroutines are? Sam <sam@email-scan.com> - 2019-08-04 09:17 -0400
  Re: Why can't I understand what coroutines are? Robert Wessel <robertwessel2@yahoo.com> - 2019-08-04 10:12 -0500
    Re: Why can't I understand what coroutines are? Juha Nieminen <nospam@thanks.invalid> - 2019-08-05 08:42 +0000
      Re: Why can't I understand what coroutines are? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-08-05 13:35 +0100
      Re: Why can't I understand what coroutines are? Bart <bc@freeuk.com> - 2019-08-05 20:19 +0100
      Re: Why can't I understand what coroutines are? Christian Gollwitzer <auriocus@gmx.de> - 2019-08-05 22:26 +0200
        Re: Why can't I understand what coroutines are? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-08-05 23:09 +0200
          Re: Why can't I understand what coroutines are? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-08-09 19:49 -0700
            Re: Why can't I understand what coroutines are? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-08-10 05:13 +0200
          Re: Why can't I understand what coroutines are? Christian Gollwitzer <auriocus@gmx.de> - 2019-08-10 08:23 +0200
            Re: Why can't I understand what coroutines are? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-08-10 10:43 +0200
              Re: Why can't I understand what coroutines are? Christian Gollwitzer <auriocus@gmx.de> - 2019-08-11 22:19 +0200
                Re: Why can't I understand what coroutines are? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-08-14 08:25 -0700
        Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-10 00:19 -0700
        Re: Why can't I understand what coroutines are? Juha Nieminen <nospam@thanks.invalid> - 2019-08-11 21:16 +0000
      Re: Why can't I understand what coroutines are? "Chris M. Thomasson" <invalid_chris_thomasson_invalid@invalid.com> - 2019-08-05 23:43 -0700
      Re: Why can't I understand what coroutines are? Bonita Montero <Bonita.Montero@gmail.com> - 2019-08-10 10:50 +0200
  Re: Why can't I understand what coroutines are? Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-08-04 17:57 +0100
  Re: Why can't I understand what coroutines are? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-08-05 01:11 +0200
    Re: Why can't I understand what coroutines are? Juha Nieminen <nospam@thanks.invalid> - 2019-08-05 08:50 +0000
      Re: Why can't I understand what coroutines are? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-08-05 16:59 +0200
    Re: Why can't I understand what coroutines are? Manfred <noname@add.invalid> - 2019-08-06 16:24 +0200
    Re: Why can't I understand what coroutines are? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-08-07 00:52 +0200
      Re: Why can't I understand what coroutines are? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-08-09 18:11 -0700
  Re: Why can't I understand what coroutines are? Martijn van Buul <pino@dohd.org> - 2019-08-05 07:46 +0000

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