[Rake-devel] An official pull request for auto-parallelizing with -j.

Hongli Lai hongli at phusion.nl
Mon Apr 20 09:14:14 EDT 2009

On Thu, Apr 16, 2009 at 6:29 AM, James M. Lawrence
<quixoticsycophant at gmail.com> wrote:
> In principle, yes, but looks can be deceiving.  A single
> over-specified or superfluous dependency can make it effectively
> linear.
> Please email me off list when you have something I can see or if you
> otherwise have questions.  I am always interested in case studies.
> http://github.com/quix/rake/blob/master/doc/parallel.rdoc might help.

Hi James.

It would seem that the problems were caused by bugs in the Rakefile.
I've fixed these bugs and parallelization seems to work fine now:

'rake nginx': 17.3 sec
'rake nginx -j 2': 13.2 sec


However, compiling everything in parallel seems to slow things down:

'rake apache2 nginx': 1 min 3 sec
'rake apache2 nginx -j 2': 1 min 9 sec

I can hear my harddisk spinning when running -j 2 so this is probably
just disk seeks slowing things down.

Sending this message to the mailing list so that Jim knows that your
code is probably OK.

Hongli Lai
Phusion | The Computer Science Company

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