Comment 1 for bug 1137060

It's a known problem. You can achieve the same result by simply launching 1000 images (if your cluster is capable of that). Eventually you hit the timeout and things get messy.

I would love to see this fixed but it's not particularly simple to solve. Nova improved things somewhat in Grizzly by switching part of the launch code flow to be an async "cast", but it's still not perfect.

Horizon is at the mercy of the APIs here by-and-large.