Re: Parallel make problem?
On Mon, Feb 04, 2008 at 02:15:49PM -0600, Bill Lear wrote:
> I just downloaded 1.5.4 and am building with gnu make, passing the '-j5'
> flag to invoke multiple jobs. I get the following:
>
> % make -j5 prefix=/opt/git-1.5.4 all doc info
I'm not sure this will ever be safe because of the recursive make invocations ('make doc' invokes '$(MAKE) -C Documentation all', which in turn does an '-include ../GIT-VERSION-FILE' which triggers a 'make -C ../ GIT-VERSION-FILE'; and that's just one of the possible problems). So you actually have three different makes running, and nothing to prevent them from clobbering each other if they hit the same file.
Show 11 quoted lines
> [...]
> make[1]: Entering directory `/home/blear/build/git-1.5.4/Documentation'
> rm -f doc.dep+ doc.dep
> /usr/bin/perl ./build-docdep.perl >doc.dep+
> Writing perl.mak for Git
> make -C ../ GIT-VERSION-FILE
> mv doc.dep+ doc.dep
> make -C ../ GIT-VERSION-FILE
> mv doc.dep+ doc.dep
> mv: cannot stat `doc.dep+': No such file or directory
> [...]
Actually, I think the particular one you're seeing is caused by the two documentation makes going at once (both 'doc' and 'info' spawn a recursive make in Documentation).
The solution is to avoid recursive make invocations, which is potentially a lot of work and not likely to happen.
The workaround, as you have may have figured out already, is:
make -j5 && make -j5 doc && make -j5 info
which should be equivalently fast, since there's plenty to parallelize within each target.
-Peff
Bill Lear