[libvirt] [PATCH 1/2] Timeout QEMU monitor replies after 30 seconds

[Eric Blake]

On 06/22/2011 09:47 AM, Daniel P. Berrange wrote:
> If the QEMU process has been stopped (kill -STOP/gdb), or the
> QEMU process has live-locked itself, then we will never get a
> reply from the monitor. We should not wait forever in this
> case, but instead timeout after a reasonable amount of time.
> 
> NB if the host has high CPU load, or a single monitor command
> intentionally takes a long time, then this will cause bogus
> failures. In the case of high CPU load, arguably the guest
> should have been migrated elsewhere, since you can't effectively
> manage guests on a host if QEMU is taking > 30 seconds to reply
> to simply commands. Since we use background migration, there
> should not be any commands which take significant time to
> execute any more
> 
> * src/qemu/qemu_monitor.c: Timeout waiting for reply after 30 seconds
> ---
>  src/qemu/qemu_monitor.c |   21 ++++++++++++++++++---
>  1 files changed, 18 insertions(+), 3 deletions(-)

This didn't make it into RC1, so I'm now torn on whether it is important
enough to be in RC2 or whether it is enough of a feature to defer to
post-0.9.3.

ACK to the code, once we decide whether (when?) to apply it.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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