[Libguestfs] [nbdkit PATCH] RFC: blocksize: Add test for sharding behavior

[Daniel P. Berrangé]

On Thu, May 26, 2022 at 09:58:50AM +0100, Richard W.M. Jones wrote:
> 
> Is there any way to do this without the literal sleeps?  Gitlab CI in
> particular appears to be very contended (I guess it runs in parallel
> on huge systems with vast numbers of unrelated containers).  I've seen
> threads being created that are so starved they never run at all even
> in tests running for many tens of seconds.

IIUC, GitLab uses GCE  "spot" VMs for its shared runners

  https://cloud.google.com/compute/docs/instances/spot

TL;DR; these are massively cheaper than normal VMs (60-91% cheaper),
but GCE might pre-empt the VM if it needs to reclaim resources for
more important VMs on the host.

IOW, we have to expect a (usually low level) of non-determinsitic
failures and stalls from the CI jobs using shared runners, and
be willing to hit the restart job button if a problem occurs.

With regards,
Daniel
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