live_debugger throwing errors on boot

[davydog187]

Bug Description

[error] GenServer LiveDebugger.Services.CallbackTracer.GenServers.TracingManager terminating
** (UndefinedFunctionError) function :elixir_compiler_0.module_info/1 is undefined (module :elixir_compiler_0 is not available)
    :elixir_compiler_0.module_info(:attributes)
    (live_debugger 0.4.0) lib/live_debugger/api/system/module.ex:53: LiveDebugger.API.System.Module.Impl.behaviours/1
    (live_debugger 0.4.0) lib/live_debugger/services/callback_tracer/queries/callbacks.ex:47: LiveDebugger.Services.CallbackTracer.Queries.Callbacks.live_behaviour?/2
    (elixir 1.18.3) lib/enum.ex:4390: Enum.filter_list/2
    (elixir 1.18.3) lib/enum.ex:4391: Enum.filter_list/2
    (live_debugger 0.4.0) lib/live_debugger/services/callback_tracer/queries/callbacks.ex:27: LiveDebugger.Services.CallbackTracer.Queries.Callbacks.all_callbacks/0
    (live_debugger 0.4.0) lib/live_debugger/services/callback_tracer/actions/tracing.ex:60: LiveDebugger.Services.CallbackTracer.Actions.Tracing.apply_trace_patterns/0
    (live_debugger 0.4.0) lib/live_debugger/services/callback_tracer/actions/tracing.ex:22: LiveDebugger.Services.CallbackTracer.Actions.Tracing.setup_tracing!/0
    (live_debugger 0.4.0) lib/live_debugger/services/callback_tracer/gen_servers/tracing_manager.ex:42: LiveDebugger.Services.CallbackTracer.GenServers.TracingManager.handle_info/2
    (stdlib 6.2.2) gen_server.erl:2345: :gen_server.try_handle_info/3
    (stdlib 6.2.2) gen_server.erl:2433: :gen_server.handle_msg/6
    (stdlib 6.2.2) proc_lib.erl:329: :proc_lib.init_p_do_apply/3
Last message: :setup_tracing
State: []
** dbg got EXIT - terminating: {undef,
                                [{elixir_compiler_0,module_info,
                                  [attributes],
                                  []},
                                 {'Elixir.LiveDebugger.API.System.Module.Impl',
                                  behaviours,1,
                                  [{file,
                                    "lib/live_debugger/api/system/module.ex"},
                                   {line,53}]},
                                 {'Elixir.LiveDebugger.Services.CallbackTracer.Queries.Callbacks',
                                  'live_behaviour?',2,
                                  [{file,
                                    "lib/live_debugger/services/callback_tracer/queries/callbacks.ex"},
                                   {line,47}]},
                                 {'Elixir.Enum',filter_list,2,
                                  [{file,"lib/enum.ex"},{line,4390}]},
                                 {'Elixir.Enum',filter_list,2,
                                  [{file,"lib/enum.ex"},{line,4391}]},
                                 {'Elixir.LiveDebugger.Services.CallbackTracer.Queries.Callbacks',
                                  all_callbacks,0,
                                  [{file,
                                    "lib/live_debugger/services/callback_tracer/queries/callbacks.ex"},
                                   {line,27}]},
                                 {'Elixir.LiveDebugger.Services.CallbackTracer.Actions.Tracing',
                                  apply_trace_patterns,0,
                                  [{file,
                                    "lib/live_debugger/services/callback_tracer/actions/tracing.ex"},
                                   {line,60}]},
                                 {'Elixir.LiveDebugger.Services.CallbackTracer.Actions.Tracing',
                                  'setup_tracing!',0,
                                  [{file,
                                    "lib/live_debugger/services/callback_tracer/actions/tracing.ex"},
                                   {line,22}]},
                                 {'Elixir.LiveDebugger.Services.CallbackTracer.GenServers.TracingManager',
                                  handle_info,2,
                                  [{file,
                                    "lib/live_debugger/services/callback_tracer/gen_servers/tracing_manager.ex"},
                                   {line,42}]},
                                 {gen_server,try_handle_info,3,
                                  [{file,"gen_server.erl"},{line,2345}]},
                                 {gen_server,handle_msg,6,
                                  [{file,"gen_server.erl"},{line,2433}]},
                                 {proc_lib,init_p_do_apply,3,
                                  [{file,"proc_lib.erl"},{line,329}]}]}
[error] GenServer LiveDebugger.Services.CallbackTracer.GenServers.TracingManager terminating
** (stop) :dbg_server_crash
    (runtime_tools 2.1.1) dbg.erl:1979: :dbg.req/1
    (live_debugger 0.4.0) lib/live_debugger/services/callback_tracer/actions/tracing.ex:13: LiveDebugger.Services.CallbackTracer.Actions.Tracing.setup_tracing!/0
    (live_debugger 0.4.0) lib/live_debugger/services/callback_tracer/gen_servers/tracing_manager.ex:42: LiveDebugger.Services.CallbackTracer.GenServers.TracingManager.handle_info/2
    (stdlib 6.2.2) gen_server.erl:2345: :gen_server.try_handle_info/3
    (stdlib 6.2.2) gen_server.erl:2433: :gen_server.handle_msg/6
    (stdlib 6.2.2) proc_lib.erl:329: :proc_lib.init_p_do_apply/3
Last message: :setup_tracing
State: []

Actual Behavior

It happens on boot, my config looks like

config :live_debugger,
  browser_features?: true,
  port: String.to_integer(System.get_env("LIVE_DEBUGGER_PORT", "4007"))

Expected Behavior

It doesn't throw errors

Steps to Reproduce

Start my app, boom

Elixir version with Erlang/OTP

1.18.3

LiveDebugger version

0.4.0

Phoenix version

1.7.21

Phoenix LiveView version

1.0.18

Operating system

MacOS

Browser(s)

Arc

[kraleppa]

Thanks, for reporting - I will take a look

[kraleppa]

@davydog187 I think I have a fix, but cannot reproduce it... deducting from your message LiveDebugger seems to call :elixir_compiler_0.module_info(:attributes).

It happens on boot because we're searching for LiveView modules by querying all available modules in the node, we execute on each module_info/1 to check their behavior.

It seems like a compiler module is for some reason returned when we query all modules... are you using any non-standard compiler? And is this bug happening all the time or it is non-deterministic?

[davydog187]

It happens on boot because we're searching for LiveView modules by querying all available modules in the node, we execute on each module_info/1 to check their behavior.

Can you point me to the code that does this?

It seems like a compiler module is for some reason returned when we query all modules... are you using any non-standard compiler?

I don't have any additional compilers defined in my mix.exs. And using a standard elixir release pulled via mise.

And is this bug happening all the time or it is non-deterministic?

Seems to happen every time on boot

[davydog187]

@kraleppa if you think #731 will fix it, i can give it a spin locally

[kraleppa]

Can you point me to the code that does this?

Sure thing, it's here

@kraleppa if you think #731 will fix it, i can give it a spin locally

Please do, and let me know if it helped

[kraleppa]

Ok I think I managed to reproduce it - it seems that this elixir_compiler module is created temporary when you need to compile something in runtime and they're purged after a while
https://hexdocs.pm/elixir/Code.html#purge_compiler_modules/0

There is a chance that you use Code.compile_string or a similar function during boot - I created a process that was using this function parallely to our module discovery function and I got serveral modules named elixir_compiler_x.

Anyway it seems that #731 fixes it

[kraleppa]

@davydog187 we released this fix in v0.4.1 😉