Comment 28 for bug 1717590

So to read through this, if a hook is never exited, then definitely it would cause starvation because only 1 hook is allowed to run. If a hook was run, exited, and then something caused it to run again, I would expect that would still provide opportunity for a different application on the same machine/container to get a chance to acquire the hook lock and run.

That said, subordinates and primaries do share a bit more exclusivity. I'm pretty sure a subordinate doesn't get set up before the primary it is associated with, but I'm guessing at that. There may be a particular time that we are waiting for (though again, guessing, something like Install hook having completed would have been enough.)

It sounds like this was fixed without changes needed from Juju, though I'm wondering if there was something you were looking for from our side? Just worried about a way to avoid lock starvation?