libvirt users - Jun 2010 - libvirt API hangs

Hi,

I have someVMs in my KVM hosts(RHEL 5.5), I found when run "virsh save
<domain> <file>" to save a VM, the command "virsh dominfo
<domain>" will
hang until the save command finishes.
Is this libvirt's behavior? Or KVM/QEMU's? This may impact the
performance.


Thanks,
Qian
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On 06/16/10 - 11:02:01PM, Zhang Qian wrote:
> Hi,
> 
> I have someVMs in my KVM hosts(RHEL 5.5), I found when run "virsh save
> <domain> <file>" to save a VM, the command "virsh
dominfo <domain>" will
> hang until the save command finishes.
> Is this libvirt's behavior? Or KVM/QEMU's? This may impact the
performance.
This is a bug in libvirtd itself, in that the threading wasn't properly
unlocking all of the time.  So the save command would take a lock for the
duration of the command, and all other commands would queue up behind it.
Recent work in libvirt should have mostly eliminated this phenomenon; you'll
want to try out libvirt 0.8.1 or later.

--
Chris Lalancette