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Groups > comp.lang.python > #79281

Re: Flush stdin

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On Sat, 18 Oct 2014 12:32:07 -0500, Tim Chase wrote:

> On 2014-10-18 17:55, Nobody wrote:
>> On Fri, 17 Oct 2014 12:38:54 +0100, Empty Account wrote:
>> 
>> > I am using netcat to listen to a port and python to read stdin and
>> > print to the console.
>> > 
>> > nc -l 2003 | python print_metrics.py
>> > 
>> > sys.stdin.flush() doesn’t seem to flush stdin,
>> 
>> You can't "flush" an input stream.
> 
> You can't flush it, but you can make it unbuffered.  You can either force
> python to use unbuffered stdio:

[snipped]

None of this helps in any way, as it's not the behaviour of the Python
script which is causing the problem, but that "nc" is (probably) buffering
its output, so the data isn't passed to the OS (let alone to the Python
script) in a timely manner.

Once the "nc" process actually write()s the data to its standard
output (i.e. desriptor 1, not the "stdout" FILE*), it will be available to
the Python script immediately thereafter without requiring any low-level
tweaks.

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Thread

Flush stdin Empty Account <emptya45@gmail.com> - 2014-10-17 12:38 +0100
  Re: Flush stdin Nobody <nobody@nowhere.invalid> - 2014-10-18 17:55 +0100
    Re: Flush stdin Tim Chase <python.list@tim.thechases.com> - 2014-10-18 12:32 -0500
      Re: Flush stdin Nobody <nobody@nowhere.invalid> - 2014-10-19 02:11 +0100
        Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-18 18:34 -0700
        Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-18 18:42 -0700
          Re: Flush stdin Nobody <nobody@nowhere.invalid> - 2014-10-22 03:49 +0100
            Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-21 20:11 -0700
    Re: Flush stdin MRAB <python@mrabarnett.plus.com> - 2014-10-18 18:55 +0100
    Re: Flush stdin Cameron Simpson <cs@zip.com.au> - 2014-10-19 08:01 +1100
    Re: Flush stdin Terry Reedy <tjreedy@udel.edu> - 2014-10-18 18:35 -0400

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