Re: [PATCH 1/1] migration: Terminate multifd threads on yank

[Leonardo Bras Soares Passos <leobras@redhat.com>]

Hello Lukas,

On Tue, Aug 3, 2021 at 3:42 AM Lukas Straub <lukasstraub2@web.de> wrote:
> Hi,
> There is an easier explanation: I forgot the send side of multifd
> altogether (I thought it was covered by migration_channel_connect()).
> So yank won't actually shutdown() the multifd sockets on the send side.

If I could get that correctly, it seems to abort migration (and
therefore close all fds) if the ft that ends up qio_channel_shutdown()
get to sendmsg(), which can take a while.
But it really does not close thew fds before that.

>
> In the bugreport you wrote
> > (As a test, I called qio_channel_shutdown() in every multifd iochannel and yank worked just fine, but I could not retry migration, because it was still 'ongoing')
> That sounds like a bug in the error handling for multifd. But quickly
> looking at the code, it should properly fail the migration.

In the end, just asking each thread to just exit ended up getting me a
smoother migration abort.
>
> BTW: You can shutdown outgoing sockets from outside of qemu with the
> 'ss' utility, like this: 'sudo ss -K dst <destination ip> dport = <destination port>'

Very nice tool, thanks for sharing!

>
> Regards,
> Lukas Straub

Best regards,
Leonardo Bras