[qemu] daemon starting instance twice if triggered on startup

[Saviq]

When an instance gets started on Multipass startup, but a client requests a start as well, daemon may try and start it twice:

$ multipass start
$ snap stop multipass
$ snap start multipass; while true; do multipass start; done
start failed: cannot connect to the multipass socket
Please ensure multipassd is running and '/var/snap/multipass/common/multipass_socket' is accessible
# ...
start failed: cannot connect to the multipass socket
Please ensure multipassd is running and '/var/snap/multipass/common/multipass_socket' is accessible
Starting primary \^C

Log excerpt:

Apr 12 13:19:47 nuc multipassd[320423]: primary needs starting. Starting now...
Apr 12 13:19:48 nuc multipassd[320423]: [322406] started: qemu-system-x86_64 --enable-kvm -cpu host -nic tap,ifname=tap-1e376645a40,script=no,downscript=no,model=virtio-net-pci,mac=52:54:00:be:37:3d -device virtio-scsi-pci,id
=scsi0 -drive file=/var/snap/multipass/common/data/multipassd/vault/instances/primary/ubuntu-20.04-server-cloudimg-amd64.img,if=none,format=qcow2,discard=unmap,id=hda -device scsi-hd,drive=hda,bus=scsi0.0 -smp 1 -m 1024M -qmp
 stdio -chardev null,id=char0 -serial chardev:char0 -nographic -cdrom /var/snap/multipass/common/data/multipassd/vault/instances/primary/cloud-init-config.iso -loadvm suspend -machine pc-i440fx-focal
Apr 12 13:19:48 nuc multipassd[320423]: Waiting for SSH to be up
Apr 12 13:19:48 nuc multipassd[320423]: QProcess: Destroyed while process ("qemu-system-x86_64") is still running.
Apr 12 13:19:48 nuc multipassd[320423]: QIODevice::read (QProcess): device not open
Apr 12 13:19:48 nuc multipassd[320423]: QMP:
Apr 12 13:19:48 nuc multipassd[320423]: QIODevice::read (QProcess): device not open
Apr 12 13:19:48 nuc multipassd[320423]: QMP:
Apr 12 13:20:18 nuc multipassd[320423]: process state changed to NotRunning
Apr 12 13:20:18 nuc multipassd[320423]: [322981] started: qemu-system-x86_64 -nographic -dump-vmstate /tmp/multipassd.wmJFCU
Apr 12 13:20:18 nuc multipassd[320423]: Applied AppArmor policy: multipass.primary.qemu-system-x86_64
Apr 12 13:20:18 nuc multipassd[320423]: process state changed to Starting
Apr 12 13:20:18 nuc multipassd[322984]: Caught an unhandled exception: Failed to apply AppArmor policy multipass.primary.qemu-system-x86_64: errno=2 (No such file or directory)
Apr 12 13:20:18 nuc multipassd[322984]: QSocketNotifier: Invalid socket 30 and type 'Read', disabling...
Apr 12 13:20:48 nuc multipassd[320423]: Qemu failed to start: program: qemu-system-x86_64; error: Process operation timed out
Apr 12 13:20:48 nuc multipassd[320423]: Caught an unhandled exception: failed to start qemu instance: program: qemu-system-x86_64; error: Process operation timed out

AFAICS it tried to dump vmstate on a running vm.

multipassd.log