Re: Auto packing the repository - foreground or background in Windows?

[Tao Klerks <tao@klerks.biz>]

Thank you all. I will try to carry forward a patch with this change
and a hint about the recommended maintenance approach for longer runs.

On Tue, Dec 6, 2022 at 11:41 PM Jeff Hostetler <git@jeffhostetler.com> wrote:
>
>
>
> On 12/6/22 1:03 PM, Derrick Stolee wrote:
> > On 12/1/2022 7:25 AM, Tao Klerks wrote:
> >> But my *question* is: Does anyone know where I could/should look to
> >> understand why the GC was happening in the foreground, even though the
> >> message says it will run in the background?
> >
> > On Windows, Git's foreground process cannot complete without also
> > killing the background process. I'm not sure on the concrete details,
> > but the lack of a background "git gc --auto" here is deliberate for
> > that platform.
>
> Here the GC code uses `daemonize()`.  On Posix this is a wrapper around
> `fork()` where the parent exits and the child continues the computation
> (without stdin/out).
>
> However, `daemonize()` just returns an ENOSYS on Windows, since Windows
> doesn't have `fork()`.  The net result is that the foreground process
> falls thru and does the actual work.
>
>
> [...]
> > Instead, the modern recommendation for repositories where "git gc --auto"
> > would be slow is to run "git maintenance start" which will schedule
> > background maintenance jobs with the Windows scheduler. Those processes
> > are built to do updates that are non-invasive to concurrent foreground
> > processes. It also sets config to avoid "git gc --auto" commands at the
> > end of foreground Git processes.
> >
> > See [1] for more details.
> >
> > [1] https://git-scm.com/docs/git-maintenance
>
> It is possible to do the GC in the background on Windows (using other
> techniques), but I don't think it is worth the bother now that we have
> `git maintenance` to handle it.
>
> And yes, AEvar's suggested fix for printing the correct error message
> looks helpful.
>
>
> Jeff