The CPU bar showed the average since the host booted, read for every
compute on every load of the VM list. The dialog now reads each compute's
graph endpoint (load over one second) when it opens, two computes at a
time so the reads hold at most two workers, and ignores answers of an
earlier opening. A host that cannot be read shows a dash. The since-boot
reading had no other caller and is removed.
The instance lists read each VM from libvirt while rendering. When that
failed, the libvirt error replaced the whole page with the error page:
one VM removed out of band, or a host that is down, took the index or
a compute's instances page with it. To avoid that, both index views
left out every VM of a host that was not connected, so users saw their
VMs disappear.
- Instance.info is None when the VM cannot be read. The row then shows
the name and owners from the database, the state "Unknown", and no
title, vCPU, memory or actions.
- Both index views list the VMs of a host that is down. The grouped
view marks the host "Not Connected" and leaves out its CPU and memory.
- A compute's instances page shows the connection error, and no longer
says the hypervisor has no instances when it cannot be reached.
Checked against the test hosts with an unreachable compute added: both
index views list its VM as unknown next to the real VMs. The first
load takes 5.5 s (one bounded connection attempt), the next ones
0.1 s. The new tests fail on the previous code (VMs left out, error
pages).
