On Tue, Jul 31, 2012 at 11:55:38AM +0200, Arie Middelkoop wrote:
> On 31/07/12 10:39, Richard W.M. Jones wrote:
> >On an unrelated topic, it'd be nice if parallel builds of coccinelle
> >worked (ie. 'make -j4').  At the moment, the build breaks randomly if
> >you do this.
> 
> I've fixed many race conditions in the Makefiles over the last
> months (since rc12 or so). We are nowadays building in parallel on
> several machines with up to 64 cores (and on my own machine only
> with 4).
> There may still be race conditions present, but in our case that
> hasn't shown up for a while now.
> 
> Most of the problems originated from the dependencies generated from
> ocamldep. In certain circumstances it would cause an interface file
> to be compiled more than once when building in parallel, leading to
> build failures because the file would be inconsistent or corrupt.
> (it's related to the -native flag to ocamldep which we cannot use in
> our setting).
> 
> Anyway, depending on the kind of build failure, it might be possible
> to find out what went wrong. If it is an instance of the above
> issue, then I could have a look at the dependencies when I would
> know which module broke and the .depend file in that directory.

Actually I see what's going on.  Our build does:

  make all opt -jNN

and I think this causes make to run the 'all' and the 'opt' builds in
parallel with each other.  I have changed this to:

  make all -jNN
  make opt -jNN

and that now seems to work.

Thanks,

Rich.

-- 
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