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

[Ken Brown]

On 2/19/2023 9:29 AM, Paul Smith wrote:
> On Sun, 2023-02-19 at 09:17 -0500, Ken Brown wrote:
> > > So I'm not sure where to go from here on Cygwin.  Should I force
> > > Cygwin builds to use the "pipe" jobserver, as I've done for
> > > GNU/Hurd?
> >
> > My preference would be for you to provide a configure option, which
> > defaults to "pipe" on Cygwin.  But if you don't want to do that, then
> > I think you should force Cygwin builds to use "pipe".
>
> There is (in my current implementation, not released yet) a way to do
> that but it's a little obscure; you need to use:
>
>   ./configure CPPFLAGS=-DJOBSERVER_USE_FIFO=0
>
> or
>
>   ./configure CPPFLAGS=-DJOBSERVER_USE_FIFO=1

That's good.

> If you set it explicitly then that setting is obeyed regardless of the
> capabilities of the system (well, if mkfifo() is not available then
> trying to enable it is a no-op of course).
>
> > > Should I add preprocessor checks (or autoconf checks?) to try to
> > > figure out which version of Cygwin is being used and choose based
> > > on that?  I don't know how to check versions.
> >
> > That wouldn't help.  There's currently no known version of Cygwin on
> > which the fifo option works well.  (Bruno tested on old version, I
> > tested the current version.)
>
> OK but I noted you said:
>
> > If I simply run 'make -j13 world' without using the Build script, it
> > doesn't hang.
>
> so I wasn't sure if we were considering that a "full failure".

I agree that it's not a full failure, but it's annoying when it happens. 
 In my use case (building TeX Live using the supplied Build script), 
the build runs for about 2 hours before it fails.

>  I guess
> if we don't know why it happens, we just have to disable mkfifo().
>
> I will change the default setting of the jobserver to use "pipe" on
> Cygwin, at least for now.

Thanks.

Ken