What happens if you omit #7 virDomainGetBlockJobInfo()? Does it still hang 1/10 times?
Yes, it still hangs.
Can you post the QEMU command-line so we know the precise VM configuration? (ps aux | grep qemu)
/usr/bin/qemu-system-x86_64 -name 68189c3c-02f6-4aae-88a2-5f13c5e6f53a -S -machine pc-i440fx-2.0,accel=kvm,usb=off -cpu SandyBridge,-kvmclock -m 1536 -realtime mlock=on -smp 2,sockets=2,cores=10,threads=1 -uuid 68189c3c-02f6-4aae-88a2-5f13c5e6f53a -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/68189c3c-02f6-4aae-88a2-5f13c5e6f53a.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,clock=vm,driftfix=slew -global kvm-pit.lost_tick_policy=discard -no-shutdown -boot menu=off,strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/mnt/nfs/volumes/7dcbd9ba-f0bc-4d3c-9b5c-b2ac824584d5/b6ed3ffc-ddca-4f10-839b-81a5b1ce371f.qcow2,if=none,id=drive-virtio-disk5,format=qcow2,cache=none,aio=threads,bps_rd=57671680,bps_wr=57671680,iops_rd=275,iops_wr=275 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk5,id=virtio-disk5,bootindex=2 -drive file=/root/rescue.iso,if=none,id=drive-ide0-0-0,readonly=on,format=raw -device ide-cd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 -netdev tap,fd=24,id=hostnet0,vhost=on,vhostfd=25 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:82:41:c9,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -vnc 0.0.0.0:2,password -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 -sandbox on
-- mg
