[Ecls-list] "make -j 4" breaks; "make" doesn't

[Juan Jose Garcia-Ripoll]

2007/2/17, Mark Hoemmen <mark.hoemmen at gmail.com>:
> I was building the 0.9i release on Itanium 2 (Debian Etch, 2.6.18
> kernel, gcc 4.1.2, no configure options other than
> --prefix=<myprefix>) and noticed that a parallel make ("make -j 4")
> fails (something like "./dpp not found") but a non-parallel make
> ("make") does not.  Not a big deal but I'm curious why a parallel make
> would fail -- isn't GNU make supposed to take care of the parallel
> issues?

It is very tricky to ensure that all dependencies are correct.
Sometimes in the makefile one lists a number of dependencies and
assumes that one is going to be performed before the rest. I am not
sure where this happens in ECL or why, but I have seen this in other
projects wher I build dependency files automatically and those files
have to be included in the makefile itself. Gnu make is not able to
cope with that.

In any case, make -j4 will not buy you anything. The only big chunk
that would benefit from parallel compilation is GMP and that you´d
rather build and install separately, if you really want to save time.

Juanjo

-- 
Dpto. de Fisica Teorica I, Fac. de CC Fisicas, Universidad Complutense,
Ciudad Universitaria s/n Madrid 28040 (Spain)
http://teorica.fis.ucm.es/~jjgarcia/