On Wed, Jan 30, 2019 at 10:46:24AM +0100, Peter Krempa wrote: > On Tue, Jan 29, 2019 at 18:52:37 +0100, Kashyap Chamarthy wrote: [...] > > Optional, a bit of explanation of "munging the output" at the start (and > > end) of the job would be useful for those new to these block APIs. > > > > Reading between the lines, and from what I recall Eric explaining once, > > what you're implying here is: that even if QEMU reported "cur==end", but > > if the _READY event is not emitted, libvirt manipulates it to report > > "cur<end". > > > > Thanks for the workaround (because "QEMU is not accurately reporting > > data") fix. > > > > /me wonders if he could make a reliable reproducer test for this... > > Technically you'll need to patch either libvirt or qemu to do so. E.g. > add a delay to processing of the READY event from qemu. This is a race > across two applications which is not easy to reproduce. Yep, noted. For now I won't spend time on it. > Also I really don't want to think this is a solution. This is a dirty > hack to work around software not willing to adapt to the correct > approach. It's not about "not willing" but the "small matter of implementing" it correctly without regressing. :-) And I realize it's not a perfect "solution", that's why I called it a workaround. And FWIW, Eric seems to agree that it is reasonable given the circumstances. > I did not want do do this, but I've found that we do something similar > for the job startup. I really hate this solution, but given that it's > two years since I've pointed out that relying on polling the info via > virDomainBlockJobInfo is broken and apps should use the _READY event > and it's still an issue today I'm going to do this, but really don't > want to advertise this as a solution. It's not a solution. It's a > hack. Right, at least for Nova, I _did_ notify upstream that the correct way is to use the events. It's a matter of prioritizing that task. (I'll file a formal bug.) -- /kashyap -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
