[libvirt] cont command failing via JSON monitor on restore

[Philipp Hahn]

Hello,

Am Donnerstag 20 Januar 2011 04:05:46 schrieb Jim Fehlig:
> I think a patch addressing the issue in the JSON monitor, where we can
> reliably detect the error, is a good start.  Would that be okay?  Also,
> recall that I cannot reproduce the issue with qemu 0.13.

We can reliably reproduct the error condition: It happens when the host is 
loaded and an additional VM is started. Sometime you have to start a VM 
several times, but we regularly experience paused VMs, which can only be 
unpaused via
  virsh qemu-monitor-command "$vm" "cont"
since libvirt thinks they are already running.

I normally hard-link the save image files to another name (*.PMH), so I can 
repeatly restore the same state again and again. Since the disk image is NOT 
snapshotted, it's content gets corrupted over time, but for testing it's 
okay. I than execute the following loop until I detect the broken state:

while virsh qemu-monitor-command "$vm" "info status" | grep running
do
  virsh destroy "$vm"
  ln "$vm.save.PMH" "$vm.save"
  virsh start "$vm"
  sleep 1
done

> Perhaps other post-0.12.5 changes have "fixed" the bug in the text monitor.

This still happens with qemu-0.14 (and in this case libvirt-0.8.7):

17:50:19.586: 29813: warning : qemudStartVMDaemon:2864 : Executing 
done /usr/bin/kvm
17:50:19.787: 29813: debug : qemuMonitorOpen:682 : New mon 0x7fad280068c0 fd 
=29 watch=61
17:50:19.787: 29813: debug : qemuMonitorSetCapabilities:905 : 
mon=0x7fad280068c0
17:50:19.787: 29813: debug : qemuMonitorGetPtyPaths:1706 : mon=0x7fad280068c0
17:50:19.787: 29813: debug : qemuMonitorCommandWithHandler:231 : Send 
command 'info chardev' for write with FD -1
17:50:19.909: 29813: debug : qemuMonitorCommandWithHandler:236 : Receive 
command reply ret=0 errno=0 83 bytes 'monitor: 
filename=unix:/var/lib/libvirt/qemu/XXX.monitor,server
'
17:50:19.909: 29813: debug : qemuMonitorGetCPUInfo:985 : mon=0x7fad280068c0
17:50:19.909: 29813: debug : qemuMonitorCommandWithHandler:231 : Send 
command 'info cpus' for write with FD -1
17:50:19.909: 29813: debug : qemuMonitorCommandWithHandler:236 : Receive 
command reply ret=0 errno=0 49 bytes '* CPU #0: pc=0x00000000fffffff0 
thread_id=5011
'
17:50:19.909: 29813: debug : qemuMonitorTextGetCPUInfo:448 : vcpu=0 pid=5011
17:50:19.909: 29813: debug : qemuMonitorSetBalloon:1116 : mon=0x7fad280068c0 
newmem=1048576
17:50:19.909: 29813: debug : qemuMonitorCommandWithHandler:231 : Send 
command 'balloon 1024' for write with FD -1
17:50:19.909: 29813: debug : qemuMonitorCommandWithHandler:236 : Receive 
command reply ret=0 errno=0 0 bytes '(null)'
17:50:19.909: 29813: debug : qemuMonitorStartCPUs:926 : mon=0x7fad280068c0
17:50:19.910: 29813: debug : qemuMonitorCommandWithHandler:231 : Send 
command 'cont' for write with FD -1
17:50:19.911: 29813: debug : qemuMonitorCommandWithHandler:236 : Receive 
command reply ret=0 errno=0 71 bytes 'An incoming migration is expected 
before this command can be executed
'

Sincerely
Philipp
-- 
Philipp Hahn           Open Source Software Engineer      hahn at univention.de
Univention GmbH        Linux for Your Business        fon: +49 421 22 232- 0
Mary-Somerville-Str.1  D-28359 Bremen                 fax: +49 421 22 232-99
                                                   http://www.univention.de/
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