Ok, so I’ve created a bunch of test cases and measured the time to entry in Application.start:
## Distillery (elixir 1.8.2-otp-21)
- date && _build/prod/rel/app/bin/app foreground: < 3 seconds
- date && _build/prod/rel/app/bin/app console: < 3 seconds
## Distillery (elixir 1.9.1-otp-21)
- date && _build/prod/rel/app/bin/app foreground: < 3 seconds
- date && _build/prod/rel/app/bin/app console: < 3 seconds
## Elixir releases (elixir 1.9.1-otp-21)
- date && _build/prod/rel/app/bin/app start: 10 seconds
- date && _build/prod/rel/app/bin/app start_iex: 10 seconds
## env MIX_ENV=prod mix phx.server --preload-modules (elixir 1.9.1-otp-21)
- date && env MIX_ENV=prod mix phx.server --preload-modules: < 3 seconds
## Experiment: Elixir releases without runtime configuration (elixir 1.9.1-otp-21)
- date && _build/prod/rel/app/bin/app start: < 3 seconds
As you can see, the Elixir releases with runtime configuration are way slower than distillery (which has the same runtime configuration). By accident I tried releases without runtime configuration and noticed this was much faster (in the same range as distellery - my feeling says it’s still a bit slower, but hard to measure/benchmark correctly so don’t trust me on this)
(Just as confirmation, my runtime configuration does nothing special, only reading environment variables and parsing a 4 values to Integer. It’s the same configuration that I use in distillery as well)
I’ve also tried: env MIX_ENV=prod mix phx.server --preload-modules which should preload and the startup speed is in the same ballpark as distillery, releases without runtime configuration.
So my conclusion is that there is something wrong with elixir releases with runtime configuration.
Maybe that’s easier to confirm for someone else?
