Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Ian Kelly <ian.g.kelly@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Other difference with Perl: Python scripts in a pipe
Date: Thu, 10 Mar 2016 15:16:04 -0700
Lines: 44
Message-ID: <mailman.159.1457648213.15725.python-list@python.org>
References: <nbsp83$2p1$1@gioia.aioe.org> <CALwzidk+8mf-nxFHtsEH+1j8wFSLPNuBtfF64kgFoy2ztWqa1Q@mail.gmail.com> <nbsral$vpa$1@ger.gmane.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
In-Reply-To: <nbsral$vpa$1@ger.gmane.org>
Precedence: list
Xref: csiph.com comp.lang.python:104558

On Thu, Mar 10, 2016 at 3:09 PM, Peter Otten <__peter__@web.de> wrote:
> I suppose you need to fill the OS-level cache:
>
> $ cat somescript.py
> import sys
>
> for i in range(int(sys.argv[1])):
>     sys.stdout.write('line %d\n' % i)
> $ python somescript.py 20 | head -n5
> line 0
> line 1
> line 2
> line 3
> line 4
> $ python somescript.py 200 | head -n5
> line 0
> line 1
> line 2
> line 3
> line 4
> $ python somescript.py 2000 | head -n5
> line 0
> line 1
> line 2
> line 3
> line 4
> Traceback (most recent call last):
>   File "somescript.py", line 4, in <module>
>     sys.stdout.write('line %d\n' % i)
> IOError: [Errno 32] Broken pipe
>
> During my experiments I even got
>
> close failed in file object destructor:
> sys.excepthook is missing
> lost sys.stderr
>
> occasionally.

Interesting, both of these are probably worth bringing up as issues on
the bugs.python.org tracker. I'm not sure that the behavior should be
changed (if we get an error, we shouldn't just swallow it) but it does
seem like a significant hassle for writing command-line
text-processing tools.