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Re: possible race condition in makefile with multiple dependencies?

  • Subject: Re: possible race condition in makefile with multiple dependencies?
  • From: Dianne Skoll <dianne [ at ] skoll [ dot ] ca>
  • Date: Thu, 3 Jun 2021 10:22:51 -0400
On Thu, 3 Jun 2021 10:19:22 -0400
"Michael P. Soulier" <msoulier [ at ] digitaltorque [ dot ] ca> wrote:

> On 2021-06-03 10:09 a.m., Dianne Skoll wrote:
> > See the -j option  

> Seems like a race condition waiting to happen.

Shouldn't be.  My understanding (which may be wrong) is that make
calculates the dependency graph first, not in parallel.  Then it
executes as many parallel tasks as the -j option asks for, or that
make sense... whichever is smaller.  Since the dependency graph is a
DAG, make should, in theory, be smart enough to see that two
dependencies depend on the same node and run only one job to build the
depended-upon node.

I routinely use "make -j `nproc`" and have never run into any issues.

Regards,

Dianne.



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