Re: Use $(MAKE) instead of 'make' in lilypond-book regtests (issue 569400043 by address@hidden)

[hanwenn]

On 2020/02/22 22:27:05, Dan Eble wrote:
> How does this interact with CPU_COUNT, which is documented in the
Contributor's
> Guide thus (emphasis mine)?
> 
>     The most time consuming task for building the documentation is
>     running LilyPond to build images of music, and *** there cannot be
>     several simultaneously running lilypond-book instances, *** so the
>     -j make option does not significantly speed up the build
>     process. To help speed it up, the makefile variable CPU_COUNT may
>     be set in local.make or on the command line to the number of .ly
>     files that LilyPond should process simultaneously, e.g. on a
>     bi-processor or dual core machine:
> 
>         make -j3 CPU_COUNT=3 doc
> 
> This is how I always build.  Is it going to have the same effect now,
or will it
> do something new, e.g. attempt 9 concurrent jobs?

if you were doing 

  make -j3 CPU_COUNT=3 

you were already potentially in a state where you have 3 jobs each
spawning 3 lp-book invocations,
as all almost everything is already doing $(MAKE) instead of 'make'.

As you can see, this only affects the regtests for lilypond-book, and
not even that, since parallelism 
is explicitly switched off for this directory (facepalm) by the
statement I marked.

There is a better reason to avoid multiple lp-book processes, though: I
am pretty sure lilypond doesn't write 
files atomically, so multiple lp-book invocations might try to write the
same files at the same time.

We should probably add locking on the .ly snippet DB so this doesn't
happen. 





https://codereview.appspot.com/569400043/