[jeffbee]

Well I hope it’s clear that this is just malpractice. Nobody should set their deadline to their p99 latency unless the result of the call is completely irrelevant to the success of the top-level request. Deadlines should be set to a huge amount of time, much longer than your tail latency but sufficiently less than infinity to protect your backend from running out of resources with too many requests in flight. For example if your p99 latency is 1ms you might set your timeout to 60s or something like that.