Re: Failed with output: Hydra job gnu:coreutils-master:build on x86_64-linux

[Bernhard Voelker]

Hi Padraig,

thanks again for working on this.

On 06/03/2013 12:13 PM, Pádraig Brady wrote:
> From 12b6c3bf70dde23c2c1bf5db7650a959f327b04f Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?P=C3=A1draig=20Brady?= <address@hidden>
> Date: Mon, 3 Jun 2013 01:29:17 +0100
> Subject: [PATCH] tests: avoid a race in tail --retry testing
> 
> Prompted by the continuous integration build failure at:
> http://hydra.nixos.org/build/5221053

Can we rely on this URL to be available quite some time, or is
there some cleanup on Hydra from time to time?

> * tests/tail-2/retry.sh: Ensure the 'out' file is not present
> as it's used to arbitrate the run order of commands.
> Relying on the truncation in the background tail command,

s/,//

> is racy because the truncation can occur after the fork
> of the background shell and thus the 'missing' file could
> be created by the time tail(1) looks for it.

I'm not sure I understand the above.
Did you mean
  s/missing/out/
  s/tail/wait4lines_/
?

> ---
>  tests/tail-2/retry.sh |   11 ++++++-----
>  1 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/tests/tail-2/retry.sh b/tests/tail-2/retry.sh
> index d56d4c1..070e4fd 100644
> --- a/tests/tail-2/retry.sh
> +++ b/tests/tail-2/retry.sh
> @@ -44,9 +44,10 @@ grep -F 'tail: warning: --retry ignored' out || fail=1
>  
>  # === Test:
>  # Ensure that "tail --retry --follow=name" waits for the file to appear.
> +rm out                                       || framework_failure_
>  timeout 10 tail -s.1 --follow=name --retry missing >out 2>&1 & pid=$!

It doesn't look obvious that rm(1) avoids a race, and someone could
easily remove that 'redundant' line again in a future change.
Would you mind to add a short comment there?

Have a nice day,
Berny