Re: |& loses data (buffering bug?)

[Vincent <zsh@hightek.org>]

On Fri, Feb 13, 2004 at 03:15:05PM +0100, Vincent Lefevre wrote:
> Contents from stdout have been lost here. The problem occurs either
> with less or with grep; for instance, a "cvs status |& grep Status"
> gave:
> 
> [...]
> File: replace_all       Status: Up-to-date
> File: rint.c            Status: Up-to-date
> File: round_prec.c      Status: Up-t
> File: set_str.c         Status: Up-to-date
> File: set_str_raw.c     Status: Up-to-date
> [...]
> 
> instead of:
> 
> [...]
> File: replace_all       Status: Up-to-date
> File: rint.c            Status: Up-to-date
> File: round_prec.c      Status: Up-to-date
> File: round_raw_generic.c       Status: Up-to-date
> File: save_expo.c       Status: Up-to-date
> File: set.c             Status: Up-to-date
> File: set_d.c           Status: Up-to-date
> File: set_dfl_prec.c    Status: Up-to-date
> File: set_exp.c         Status: Up-to-date
> File: set_f.c           Status: Up-to-date
> File: set_inf.c         Status: Up-to-date
> File: set_ld.c          Status: Up-to-date
> File: set_nan.c         Status: Up-to-date
> File: set_prc_raw.c     Status: Up-to-date
> File: set_prec.c        Status: Up-to-date
> File: set_q.c           Status: Up-to-date
> File: set_rnd.c         Status: Up-to-date
> File: set_si.c          Status: Up-to-date
> File: set_str.c         Status: Up-to-date
> File: set_str_raw.c     Status: Up-to-date
> [...]
> 
> When I redirect the output of the second command to a file, it seems
> that the problem never occurs.
> 
> Is it a bug from zsh (I'm using zsh 4.0.9) or from cvs?

That is weird.  It looks to me like you might be encountering YALKB
(Yet Another Linux Kernel Bug) :-).  I just tested the "cvs status |&
grep Status" command on FreeBSD with zsh-4.1.1 and get no data loss.
You might want to try a different version kernel and see if it still
does it.

Another way to confirm one way or the other, if you have a machine to
test on, is to install FreeBSD and run the same linux binaries of zsh
and cvs on it with the linux_base package installed (for running Linux
binaries) and see if the problem still exists.  We discovered that
many of the bugs and instabilities we had wrongly blamed for a long
time on applications such as our in-house CAD system did not exist on
FreeBSD, even running the same binaries, without re-compiling native
to FreeBSD.

We left Linux well over a year ago after almost 10 years of usage
because of all the crashes and weird memory management bugs and all of
the weird problems went away.