Re: Regression on Cygwin: Problems with parallel make in 4.4

[Paul Smith]

On Mon, 2023-02-20 at 20:21 -0500, Ken Brown wrote:
> Parallel make is still not working reliably.  I've just discovered
> that my TeX Live build logs have several occurrences of the following
> warning:
> 
>    jobserver unavailable: using -j1.  Add '+' to parent make rule.
> 
> This has been going on since I first started using 4.4.0.90 with the 
> jobserver style set to "pipe".  It *only* occurs when the jobserver
> uses a pipe.  Two others in the Cygwin community are reporting the
> same thing when they build projects using cmake (with Unix Makefiles
> and make 4.4.0.91).

Just to note, I do run the regression test suite with the equivalent of
"jobserver-style=pipe" (basically I force the configure to believe that
the system doesn't support mkfifo() so it falls back to "pipe" mode).

Can you run builds with GNU Make 4.4 and --jobserver-style=pipe?  Do
you see the same warnings there?  I just want to know if the problem
happened in 4.4 or post-4.4.  If the latter, that's very odd.  If the
former, it's more understandable because we did make the "pipe" mode
more strict in 4.4.

This message means only one thing: the parent make didn't provide the
proper environment (that is, the correct file descriptors) to its sub-
make.  However, there could be different ways in which the environment
is wrong.

If you have the ability, it would be helpful if you could apply the
attached patch to your build of GNU Make and try the build again, and
let me know which of these different messages are generated right
before the above error.

It would also be very helpful if someone could provide me with the
complete rule that the parent make uses to invoke the sub-make, where
that message appears.  And, if you can include the output that make
generates to invoke the submake (the command it prints) that would be
excellent as well.

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