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Groups > comp.lang.python > #79412

Re: Flush stdin

From Marko Rauhamaa <marko@pacujo.net>
Newsgroups comp.lang.python
Subject Re: Flush stdin
Date 2014-10-22 08:38 +0300
Organization A noiseless patient Spider
Message-ID <871tq0fyun.fsf@elektro.pacujo.net> (permalink)
References (4 earlier) <mailman.15012.1413845578.18130.python-list@python.org> <87mw8qfhza.fsf@elektro.pacujo.net> <mailman.15019.1413851421.18130.python-list@python.org> <87h9yyf318.fsf@elektro.pacujo.net> <mailman.15049.1413933396.18130.python-list@python.org>

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Dan Stromberg <drsalists@gmail.com>:

> On Mon, Oct 20, 2014 at 9:41 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
>> Nagle affects the communication between the peer OS kernels and isn't
>> directly related to anything the application does.
>
> Actually, Nagle can cause two or more small packets to be merged,
> which is something an application must be able to deal with, because
> they could show up in the receiving application as one or more (but
> anyway: fewer) merged recv()'s.

Packets have barely anything to do with TCP sockets since they provide
an octet stream abstraction.

> Of course, but who's doing one byte per second?  You and I in our
> tests, and perhaps some application developers with remarkably
> undemanding I/O.  That doesn't really mean we should _recommend_ a
> series of os.read(0, 1)'s.

No, here's my statement: if you need to process input as soon as it
becomes available, you can't use sys.stdin. Instead, you need to use
os.read().

You typically supply os.read() with a buffer of a kilobyte or more. Key
is, os.read() returns right away if fewer bytes are available.


Marko

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Thread

Re: Flush stdin Cameron Simpson <cs@zip.com.au> - 2014-10-20 14:56 +1100
  Re: Flush stdin Marko Rauhamaa <marko@pacujo.net> - 2014-10-20 07:45 +0300
    Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-20 14:59 -0700
      Re: Flush stdin Marko Rauhamaa <marko@pacujo.net> - 2014-10-21 01:54 +0300
    Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-20 15:52 -0700
      Re: Flush stdin Marko Rauhamaa <marko@pacujo.net> - 2014-10-21 02:18 +0300
        Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-20 17:30 -0700
          Re: Flush stdin Marko Rauhamaa <marko@pacujo.net> - 2014-10-21 07:41 +0300
            Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-21 16:16 -0700
              Re: Flush stdin Marko Rauhamaa <marko@pacujo.net> - 2014-10-22 08:38 +0300
                Re: Flush stdin Chris Angelico <rosuav@gmail.com> - 2014-10-22 17:23 +1100
              Re: Flush stdin Marko Rauhamaa <marko@pacujo.net> - 2014-10-22 13:57 +0300
            Re: Flush stdin random832@fastmail.us - 2014-10-22 11:01 -0400
              Re: Flush stdin Marko Rauhamaa <marko@pacujo.net> - 2014-10-22 18:28 +0300

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