How to run Rust code from Elixir with --release mode?


I need to read millions rows via rust , do some modification and return final result (some stats) to elixir apps via rustler .

When I run rust code with :
cargo run it takes 40 sec.
cargo run --realease it takes 1,5 sec.

but when I run it from Elixir via rustler/nif from iex -S mix it takes 40 sec.
How to run it so fast in similar way like cargo run --release mode, from elixir apps ?

Thanks for help .

1 Like

Rustler by default uses the MIX_ENV to determine how to build the nif, if you’re using iex -S mix the default MIX_ENV is :dev, which compiles the nif in debug mode (the 40 seconds use case).

To compile the nif in release mode you can either pass the MIX_ENV to the iex command MIX_ENV="prod" iex -S mix or you can pass mode: :release in the nif config itself, the config options can be found here.


Thanks a lot. Now it works fast