[erlang-bugs] Erlang 18.0-rc1 is behaving slower than 17.4 (and 17.5)

[José Valim]

I have benchmarked with Erlang 18.0-rc2 and all the issues I have mentioned
here have been resolved.

Thanks OTP!



*José Valim*
www.plataformatec.com.br
Skype: jv.ptec
Founder and Lead Developer

On Wed, Apr 8, 2015 at 12:44 AM, José Valim <jose.valim@REDACTED
> wrote:

> I have first noticed this issue when compiling Elixir's grammar. Compiling
> yrl -> erl -> beam is about 20% slower in Erlang 18.0-rc1. The results are
> shown below:
>
> https://gist.github.com/josevalim/ab08341512ba875fb4a7
>
> To further verify the performance issues, I have decided to run Elixir's
> test suite with 18.0 and 17.4. Elixir test suite defines a lot of modules
> dynamically when loading so that would be a good test. The results are here:
>
> https://gist.github.com/josevalim/895e2365d5ae517b1c8a
>
> It is interesting that the load/compile times are indeed higher in 18.0
> but the test suite is also taking *longer*. This may imply it is not the
> compiler that is slower but Erlang itself. I have run the test suite of
> other projects in different Erlang versions (same Elixir version though)
> and seen similar slow down. About a 20% slow down on Erlang 18.0-rc1
> overall.
>
> Unfortunately, I don't have any idea why this is happening. I have asked
> others to compile the same .yrl file and they have seen similar performance
> hit. It is easy to reproduce it. Download the elixir_parser.yrl file:
>
>
> https://github.com/elixir-lang/elixir/blob/v1.0/lib/elixir/src/elixir_parser.yrl
>
> And run both commands:
>
>     $ time erlc +time elixir_parser.yrl
>     $ time erlc +time elixir_parser.erl
>
> I hope by posting this report others can be alert to similar issues in
> their projects.
>
> Thoughts?
>
> *José Valim*
> www.plataformatec.com.br
> Skype: jv.ptec
> Founder and Lead Developer
>
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