Re: [libvirt] [PATCH 0/5] Introduce VIR_CONNECT_GET_ALL_DOMAINS_STATS_BEST_EFFORT
On 06/07/2018 02:53 PM, Daniel P. Berrangé wrote:
On Thu, Jun 07, 2018 at 01:59:11PM +0200, Michal Privoznik wrote:
> Problem is, if there is a long standing job on a domain fetching
> statistics might hiccup which might be a problem for mgmt apps that
> query stats every few seconds.
>
> Orthogonal to this, I think we should break our sync QEMU_JOB_* into two
> separate jobs: one for qemu monitor the other for qemu guest agent.
> Problem is, if thread A grabs QEMU_JOB_MODIFY and talks only to guest
> agent it prevents thread B from grabbing QEMU_JOB_QUERY which wants to
> talk only to qemu monitor. But this is a different can of worms and I
> haven't thought it through completely just yet.
Yeah, I think that is important todo because the guest agent is untrusted
service and so can arbitrarily delay its response to libvirt. Even though
we timeout the agent after a while, we shouldn't really let it delay other
APIs using the monitor.
Indeed. I'm working on it as we speak. Nevertheless, these patches are
independent of that (in case any reviewer is waiting for those patches
first).
Michal