rerdos
Time accuracy within intervals
I have a question about Elixir/Erlang time precision.
defmodule Test do
use GenServer
def start_link do
GenServer.start_link(__MODULE__, [], name: __MODULE__)
end
def init(state) do
next()
{:ok, state}
end
def handle_info(:next, state) do
spawn_link(fn -> IO.puts :os.system_time(:millisecond) end)
next()
{:noreply, state}
end
defp next() do
Process.send_after(self(), :next, 50)
end
end
The average delay I’m getting between calls is around 62.5ms.
iex(1)> 1609107565704
iex(1)> 1609107565768
iex(1)> 1609107565831
iex(1)> 1609107565893
iex(1)> 1609107565955
iex(1)> 1609107566018
iex(1)> 1609107566081
iex(1)> 1609107566145
I’m running the Test module isolated from the rest of the app on a relatively new piece of hardware. I wonder if there is a way to get more accurate intervals - or if I’m doing something wrong?
Marked As Solved
lud
I get 51ms difference with your code. This is expected because between receiving a message and starting a new timeout you have computations.
You may want to use :timer.send_interval:
defmodule Test do
use GenServer
def start_link do
GenServer.start_link(__MODULE__, [], name: __MODULE__)
end
def init(state) do
:timer.send_interval(50, :next)
{:ok, state}
end
def handle_info(:next, state) do
IO.puts :os.system_time(:millisecond)
{:noreply, state}
end
end
2
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