[Webkit-unassigned] [Bug 64669] [Gtk] [NRWT] Xvfb produces a lot of stderr output

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Mon Jul 18 14:14:41 PDT 2011


Philippe Normand <pnormand at igalia.com> changed:

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--- Comment #2 from Philippe Normand <pnormand at igalia.com>  2011-07-18 14:14:42 PST ---
(From update of attachment 101116)
View in context: https://bugs.webkit.org/attachment.cgi?id=101116&action=review

> Tools/Scripts/webkitpy/layout_tests/port/gtk.py:46
> +        self._xvfb_process = subprocess.Popen(run_xvfb, stderr=subprocess.PIPE)


recommends to open /dev/null instead.

Quoting the interesting comment:

If your search engine lead you to this old question (like me), be aware that Manuel's solution (at this time the most valued), namely using PIPE can lead to deadlocks.

Indeed, because pipes are buffered, you can write a certain number of bytes in a pipe, even if no one read it. However the size of buffer is finite. And consequently if your program A has an output larger than the buffer, A will be blocked on writing, while the calling program B awaits the termination of A.

So the preferred solution would be something like:

devnull = open(os.devnull, 'w')
self._xvfb_process = subprocess.Popen(run_xvfb, stderr=devnull)

Can you please check this would work?

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