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

[Paul Smith]

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

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 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.