I don't understand what you mean by this. Sending SIGUSR1 doesn't mean that the async isn't queued; it's still put into the system_apc list. SIGUSR1 doesn't carry the async as a payload or anything, it's just a way to force the thread to check its own queue. Am I missing something here?
Oops, sorry… no, it is me missing an obvious fact which I knew for years, something made me see the problem where there is not. I will update the patch.