Re: Parallel make problem with git master

Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Where it doesn't work is in the other subdirs, c.f. the current problem
> with interfaces/libpq and interfaces/ecpg. It would be a lot more
> difficult to fix there, I think, but maybe I'm wrong.

Right, it's specifically the interdependence between ecpg and libpq
that's causing the main symptom Jeff is complaining of. Although when
I was trying "make -j12 install" starting from a clean tree yesterday,
I did see at least one failure in the backend. It's all pretty
timing-dependent --- if you look at the make output, you can clearly
see that the same sub-make tasks get launched repeatedly due to various
makefiles trying to force prerequisites in other parts of the tree to be
up to date. (Which is exactly one of the band-aid fixes that Miller
talks about.) If two such tasks get launched close enough to the same
time, they both try to do the same work, and then you get failures like
"ln" complaining that the target is already there, or "ar" complaining
that somebody corrupted its output file, etc etc.

I think Miller's analysis is dead on and we ought to think seriously
about adopting his approach. Obviously this is not a small task...

regards, tom lane