Re: Add a cooperative FS lock to lilypond-book. (issue 555360043 by address@hidden)

[dak]

On 2020/02/23 15:59:14, hahnjo wrote:
> On 2020/02/23 15:54:54, hanwenn wrote:
> > I think this is worth it because it simplifies the build system, and
puts the
> > locking in the place where we actually access the resource.
> 
> Let me disagree: It complicates lilypond-book with something that no
(external)
> user of the script cares about. So IMHO adding brittle locking
requires more
> justification than that.
> 
> > I take your point about dropped files; the best would be fcntl
locks, but I am
> > worried that they might not be supported on windows. Would you know?
> > 
> > Maybe we can just use fcntl locks on unix, and Windows users should
just not
> try
> > to run parallel lp-book invocations.
> 
> Can we please first take a step back and see how much benefit there
actually is?

To be fair, the current situation is that _anybody_ should just not try
to run parallel lp-book invocations, whether from our build system,
started manually from different shells with the same database, or in any
other manner.  The lilybook database is quite a big hack with its main
purpose being speeding up our doc build.  I am not quite sure whether
normal lilypond-book invocations would even use it.  If they do, the
lock might be separately useful to what is going on in our build
process.

https://codereview.appspot.com/555360043/