Release boot halts, if :io is used inon_load #14960
Description
Elixir and Erlang/OTP versions
Erlang/OTP 28 [erts-16.1.2] [source] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [jit]
Elixir 1.19.3 (compiled with Erlang/OTP 28)
Operating system
Mac OS 26.1 (but probably others as well)
Current behavior
The issue came out in a corporate software, but I could reproduce it on a small example.
I've just genersted a new Elixir app with mix (mix new loader --app loader) and added the following small Erlang file to the src folder and of course added that folder to the erlc_paths
-module(loader_erl).
-on_load(init/0).
init() ->
io:format("Loader Erlang module loaded successfully.~n"),
ok.
The iex -S mix command works just fine (though no io is visible), but if I make a release with mix release (can be dev and prod as well), and I would like to start from the release it halts.
In the bash file I've modified a bit, that loading script, I've added this: -init_debug
start () {
export_release_sys_config
REL_EXEC="$1"
shift
exec "$REL_VSN_DIR/$REL_EXEC" \
--cookie "$RELEASE_COOKIE" \
$(release_distribution "$RELEASE_NODE") \
--erl "-mode $RELEASE_MODE -init_debug" \
--erl-config "$RELEASE_SYS_CONFIG" \
--boot "$REL_VSN_DIR/$RELEASE_BOOT_SCRIPT" \
--boot-var RELEASE_LIB "$RELEASE_ROOT/lib" \
--vm-args "$RELEASE_VM_ARGS" "$@"
}So I could see where it holds.
...
old,500},{discard_threshold_periodic_check,30000},{metadata,[]}]},{maxT,infinity},{maxP,infinity},{mod,{'Elixir.Logger.App',[]}}]}]}}
{done_in_microseconds,10}
{apply,{application,load,[{application,loader,[{description,"loader"},{vsn,"0.1.0"},{id,[]},{modules,['Elixir.Loader',loader_erl]},{registered,[]},{applications,[kernel,stdlib,elixir,logger]},{optional_applications,[]},{included_applications,[]},{env,[]},{maxT,infinity},{maxP,infinity}]}]}}
{done_in_microseconds,3}
{progress,applications_loaded}
{apply,{application,start_boot,[kernel,permanent]}}
{running_on_load_handler,loader_erl}
The similar behaviour works with rebar3.
Source code: loader.zip
Expected behavior
The release should start