Possible memory leak when using linked processes

[danifv]

I'm doing some measurements on resource usage (memory and power mainly) and found a possible memory leak.
When spawning linked processes that end normally, the available Free Heap is lower than before starting the processes.
e.g.

f() ->
    [spawn_link(fun() ->  timer:sleep(500) end) || _ <- lists:seq(1, 50)].

In contrast, when spawning linked processes that terminate, the available Free Heap is more or less the same as before starting the processes.
e.g.

f() ->
    [spawn(fun() ->  ephemeral_start() end) || _ <- lists:seq(1, 50)].

ephemeral_start() ->
    spawn_link(fun() -> ephemeral() end).

ephemeral() ->
    timer:sleep(500),
    exit(normal).

I suspect, that memory related to the link remains allocated.

I'm doing the measurements on an ESP32 system.

[pguyot]

Is this related to this comment?

AtomVM/src/libAtomVM/context.c

Line 392 in fc824ad

// TODO: we should scan for existing monitors when a context is destroyed

[danifv]

It could possibly be if that code also relates to links.
However I can confirm that a similar leak also occurs when monitoring spawned processes:

f() ->
    Pids = [spawn(fun() -> timer:sleep(500) end) || _ <- lists:seq(1,N)],
    [erlang:monitor(process, P) || P <- Pids].

[pguyot]

Links are handled internally there, this is the case where monitor->ref_ticks == 0.