perf: Improve Runner tick signaling on macrotask-only wait#2999
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karlseguin
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Currently, Runner assumes that HttpClient.tick did something. But it's possible
that HttpClient had nothing to do, and thus didn't poll. In that case, Runner
would return .{.ok = 0} and Runner's caller would also certainly call
Runner.tick again, resulting in a spin-loop.
The reason Runner allows this to happen is because it can still have macrotasks
to run. So now, when HttpClient.tick has done nothing, Runner will return its
ms_to_next_task, rather than 0.
On sites where all i/o is completed, and only macrotasks are waiting, this
significantly reduces CPU usage.
karlseguin
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Currently, Runner assumes that HttpClient.tick did something. But it's possible that HttpClient had nothing to do, and thus didn't poll. In that case, Runner would return .{.ok = 0} and Runner's caller would also certainly call Runner.tick again, resulting in a spin-loop.
The reason Runner allows this to happen is because it can still have macrotasks to run. So now, when HttpClient.tick has done nothing, Runner will return its ms_to_next_task, rather than 0.
On sites where all i/o is completed, and only macrotasks are waiting, this significantly reduces CPU usage.
(This is part of ongoing work for #1507)