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From: Lowell Gilbert <freebsd-stable-local@be-well.ilk.org>
To: Walter Parker <walterp@gmail.com>
Cc: freebsd-stable@freebsd.org
Subject: Re: Building Kernel and World with -j
References: <CAMPTd_A+e6JCJ8SPLGVh4M2Jb=ZLqHDWN9y8JLcVHgWO0=zJ8Q@mail.gmail.com>
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 (Walter Parker's message of "Sun, 22 Jan 2017 22:57:46 -0800")
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Walter Parker <walterp@gmail.com> writes:

> For decades there has always been a warning not to do parallel builds of
> the kernel or the world (Linux kernel builds also suggest not to do this).
>
> Every once in a while, I see people post about 5 minutes. This only way I
> can see this happening is by doing a parallel build (-j 16 on a Xeon
> Monster box).
>
> Are parallel builds safe? If not, what are actual risk factors and can they
> be mitigated?

As a general rule, it's safe. But don't report failures from a
parallel build.

This is not so much an issue of parallel builds being unsupported
as of the logs being harder to read.