[Libguestfs] [PATCH libnbd 2/2] socket-activation: Allow multiple connections

[Nir Soffer]

On Sun, Nov 7, 2021 at 4:26 PM Richard W.M. Jones <rjones at redhat.com> wrote:
>
> On Sun, Nov 07, 2021 at 04:22:26PM +0200, Nir Soffer wrote:
> > On Sun, Nov 7, 2021 at 4:00 PM Richard W.M. Jones <rjones at redhat.com> wrote:
> > >
> > > On Sun, Nov 07, 2021 at 03:27:47PM +0200, Nir Soffer wrote:
> > > > When using qemu-nbd with systemd socket activation, trying to connect
> > > > additional clients concurrently fails with:
> > > >
> > > >     nbd_connect_uri: connect: server backlog overflowed, see
> > > >     https://bugzilla.redhat.com/1925045: Resource temporarily
> > > >     unavailable
> > > >
> > > > But this bug was fixed in qemu-nbd long time ago; turns out that libnbd
> > > > has the same bug, creating the server socket with:
> > > >
> > > >     listen(s, 1);
> > > >
> > > > Use SOMAXCONN so we can have multiple connections for better
> > > > performance. I think this can be very useful for nbdcopy.
> > >
> > > Apart from the problems in API mentioned in the other review, this
> > > patch ordering isn't bisectable.
> > >
> > > What's the motivation for this patch series?
> >
> > Why is it not bissectable?
>
> Doesn't the test fail after the first patch is applied and
> before the second one?

No, it requires using concurrent connections to fail. I have an application
using this that fails reliably without the fix.