Re: Adds redirect-lilypond-output option to lilypond-book(issue4664060)

[Graham Percival]

On Wed, Jul 13, 2011 at 03:26:18PM +0100, Phil Holmes wrote:
> ----- Original Message ----- From: "David Kastrup" <address@hidden>
> To: <address@hidden>
> >address@hidden writes:
> >
> >>in light of the growing consensus for "combined" logfiles for the build
> >>system -- and given that lilypond only produces stuff on stderr and
> >>apparently this isn't going to change -- I wonder if it might be better
> >>to redirect both stdout and sterr to a single .log file.
> >
> >Redirecting two file pointers to the same file has a tendency to wreak
> >havoc with buffering.
> >
> >So it is not something I am overly comfortable with.

ok, if/when we add this, we'd use a different way of recording
output.  I'm certain that python's subprocess module has some way
of doing this.

> My understanding (which is certainly not perfect) is that one of the
> stream is buffered (stdout from memory, without checking) and the
> other isn't, so that the worst that happens is that the lines are
> not quite in the order that might be expected.

That "worst that happens" is beyond what's acceptable.  Seeing an
error message before the command that causes the error?  That
could easily chew up 10 hours of fruitless debugging while
somebody investigates a perfectly good command.

In light of this, let's go ahead with the separate log files for
now.

Cheers,
- Graham