:binary.split only works on binaries and os:getenv/0 returns a list of lists.
On Tuesday, August 18, 2020 at 4:04:00 AM UTC-4, alco wrote: > > The use of String.split instead of :binary.split seems excessive here. > Could be a small but quick win. > > On Tue, Aug 18, 2020 at 9:03 AM José Valim <jose...@dashbit.co > <javascript:>> wrote: > >> We need to go route 2, as 1 can change at any time (including if 2 is >> implemented). So thank you for opening an issue on Erlang's issues tracker, >> I am now watching it and I can act based on its status. :) >> >> On Mon, Aug 17, 2020 at 11:45 PM Trevor Brown <ad...@stratus3d.com >> <javascript:>> wrote: >> >>> Background >>> >>> I was recently working on a project that invoked `System.get_env/0` on >>> every request it handled. Someone changed the infrastructure the >>> application was deployed on and greatly increased the number of environment >>> variables (3x more) in the environment the Elixir application ran in, and >>> the performance of the application degraded by about that same amount (3x >>> slower than before). When I profiled the application I quickly found that >>> most of the request handling was spent waiting for the `System.get_env/0` >>> function to return. I changed the code so `System.get_env/0` was only >>> invoked on startup and the performance issue was resolved. >>> >>> Problem >>> >>> When I was working on the performance issue in the app the flame graphs >>> revealed something interesting - Erlang was actually formatting the >>> environment variables from a proplist to a list of strings in certain >>> format, and then Elixir was undoing the formatting by parsing the strings >>> back to a map! Because of this the performance of the `System.get_env/0` >>> function call is tied to the number of variables in the environment. >>> >>> >>> - The Erlang code that formats the variables: >>> https://github.com/erlang/otp/blob/master/lib/kernel/src/os.erl#L118 >>> - The Elixir code that parses them and puts them in a dictionary: >>> >>> https://github.com/elixir-lang/elixir/blob/v1.10.3/lib/elixir/lib/system.ex#L438 >>> >>> >>> Possible Solutions >>> >>> *1. Update the `System.get_env/0` function to use `os:list_env_vars/0` >>> function* >>> >>> This function already exists returns a proplists in the format >>> `{VariableName, VariableValue}`. All we need to do is replace the existing >>> code with >>> >>> def get_env do >>> Enum.into(:os.list_env_vars(), %{}) >>> end >>> >>> This would solve the performance issue and simplify the Elixir code! The >>> downside is that `os:list_env_vars/0` is not a documented function, which I >>> assume means it's not recommended for other applications to rely on it. >>> >>> *2. Wait for Erlang to change* >>> >>> Because I assumed `os:list_env_vars/0` is not a function that Elixir >>> should be relying on (although nothing prevents it from doing so), I have >>> created an enhancement ticket on the Erlang issue tracker to document >>> `os:list_env_vars/0` or implement another function that returns the >>> environment variables in a proplist with `{VariableName, VariableValue}` >>> tuples - https://bugs.erlang.org/browse/ERL-1332. >>> <https://bugs.erlang.org/browse/ERL-1332> Once Erlang implements a >>> documented function that does this we could then begin updating Elixir. >>> >>> Thoughts? I doubt this is something that is run into very often but it >>> could be easily improved. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "elixir-lang-core" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to elixir-l...@googlegroups.com <javascript:>. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/0aecb090-2cbb-46af-8ff4-e34337b123d4o%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/elixir-lang-core/0aecb090-2cbb-46af-8ff4-e34337b123d4o%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "elixir-lang-core" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to elixir-l...@googlegroups.com <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4KHzHHTw_mU6vCUoK3yPYT5cQQBWicMkQ5cGTpZTmT26Q%40mail.gmail.com >> >> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4KHzHHTw_mU6vCUoK3yPYT5cQQBWicMkQ5cGTpZTmT26Q%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > > > -- > Best regards > Alexei Sholik > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-core+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/c3b36f04-4062-42d9-ba7d-7aa5fda8134ao%40googlegroups.com.
