From: Robert Klemme <bob.news@...>
Date: 2003-05-08T20:50:29+09:00
Subject: Re: IO.pipe + thread = hangs (was: Re: capture output)

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<nobu.nokada@softhome.net> schrieb im Newsbeitrag
news:200305081052.h48AqYeR008509@sharui.nakada.kanuma.tochigi.jp...
> Hi,
>
> At Thu, 8 May 2003 16:49:22 +0900,
> Robert Klemme wrote:
> > A bit more testing reveals that this seems to be a problem of the
mswin
> > version:
>
> IO multiplexing on pipes doesn't work on Windows.  It's a known
> restriction.

Ah!  Thanks a lot for clearing this!  I would have thought that a file
descriptor pointing to a pipe end is the same as a file descriptor
pointing to a terminal or file, but then - it's windows... *sigh*

> > I noticed also, that closing STDERR or $stderr does seem to close
STDOUT,
> > too.  Is this intended behavior or is it a known bug?
>
> Neither.  Could you detail?  This worked for me, at least.
>
> $ ruby16-mswin -e 'STDERR.close; puts "hello"'
> hello

True for me, too.  Apparently I draw the wrong conclusion while
experimenting with pipe redirecting.  One of the scripts I was using for
experiments (see attached) did seem to eat STDOUT output when STDERR was
closed.  Strange, though.

Kind regards

    robert

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#!/usr/bin/ruby -w=0A=
=0A=
STDOUT.sync=3D true=0A=
=0A=
rd, wr =3D IO.pipe=0A=
=0A=
reader =3D Thread.new do=0A=
  buffer =3D ""=0A=
=0A=
  rd.each do |line|=0A=
    buffer << line=0A=
  end=0A=
=0A=
  rd.close=0A=
=0A=
  buffer=0A=
end=0A=
=0A=
# when uncommenting the next line NO output occurs,=0A=
# even STDOUT is silent:=0A=
# STDERR.close=0A=
STDERR.reopen wr=0A=
=0A=
puts "Sending message to parent"=0A=
STDERR.write "Hi Dad"=0A=
wr.close=0A=
=0A=
puts "Parent got: <#{reader.value}>"=0A=

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