[libvirt] [Xen-devel] [PATCH 00/12] libxl: fork: SIGCHLD flexibility
Daniel P. Berrange
berrange at redhat.com
Thu Jan 30 16:17:30 UTC 2014
On Thu, Jan 30, 2014 at 09:14:01AM -0700, Jim Fehlig wrote:
> Daniel P. Berrange wrote:
> > On Mon, Jan 27, 2014 at 06:39:36PM -0700, Jim Fehlig wrote:
> >
> >> [Adding libvirt list...]
> >>
> >> Ian Jackson wrote:
> >>
> >>> Jim Fehlig writes ("Re: [Xen-devel] [PATCH 00/12] libxl: fork: SIGCHLD flexibility"):
> >>>
> >
> > BTW, I meant to ask before - what is the SIGCHLD reference about in the
> > subject line ?
> >
>
> This is related to child processes started by libxl. E.g. running a
> bootloader when creating PV VMs, running a save/restore helper when
> saving/restoring a VM, etc.
>
> > libvirt drivers that live inside libvirtd should never use or rely on
> > the SIGCHLD signal at all. All VM processes started by libvirtd ought
> > to be fully daemonized so that their parent is pid 1 / init. This ensures
> > that the libvirtd daemon can be restarted without all the VMs getting
> > reaped. Once the VMs are reparented to init, then libvirt or library
> > code it uses has no way of ever receiving SIGCHLD.
> >
>
> Nod. VMs are "daemonized", in the context of Xen. Once running,
> libvirtd can be restarted without reaping them.
Great, thanks for clarifying, this sounds fine then.
Daniel
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