[Qemu-discuss] Qemu Socket Backend Reliablility / Retry

[Josh Powers]

Hello All,

I am fairly new to the QEMU world but I have been using it for a few
weeks now and it is amazing, solving a lot of problems for me.

However I have encountered one problem I haven't found a good solution
around. I am spinning up QEMU instances automatically then configuring
their network backend to connect over a socket at run time through the
QEMU console.  I have noticed however that occationally if I startup
the listen end and too quickly start up the connect end it will fail
to connect, presumably the listen end isnt initialized yet.

At any rate I have "solved" this problem by adding an arbitrary delay
to my tool that is spinning the vm's up but that is not a good
perminant solution.  I have been diging around trying to figure out if
there is some way to get the connect end to continue to retry if it
fails to connect or to get an easy to parse verification that the
listen end is ready for the connect end.

Any ideas?  I had considered using multicast as a side note since the
order of the connections dont matter however I have restrictions that
prevent me from using multicast.  The virtual machines are being spun
up on different servers (or at least can be) so as far as I know my
backend does need to be a socket not one of the other options. Also I
am intending to connect the two instances directly "as though by a
wire" so I dont want to use the other options like tap etc.

Thanks in advance for your time,
Josh Powers