Hello,
I have some GenServers that will do some loading during init function using Task.async (so they will not block init and then get the result via handle_info function).

Recently I noticed that for the period that this task is running, the :observer Applications tab, with the app tab in which the caller server is supervised, will freeze and not respond until the task finishes its job. I have other GenServers that start Tasks for other stuff and they don’t show the same behavior.

I also get some errors from appmon during that period:

12:48:14.862 [error] #PID<0.741.0> :gen_server "error_info/7" "gen_server.erl" 889 
        GenServer :appmon_info terminating
** (MatchError) no match of right hand side value: {:error, {:EXIT, {:badarg, [{:erlang, :element, [2, :undefined], []}, {:appmon_info, :check_sasl_ancestor, 2, [file: 'appmon_info.erl', line: 618]}, {:appmon_info, :maybe_add_child_sasl, 4, [file: 'appmon_info.erl', line: 590]}, {:lists, :foldr, 3, [file: 'lists.erl', line: 1276]}, {:appmon_info, :do_find_proc2, 5, [file: 'appmon_info.erl', line: 497]}, {:appmon_info, :calc_app_tree, 2, [file: 'appmon_info.erl', line: 450]}, {:appmon_info, :do_work, 2, [file: 'appmon_info.erl', line: 308]}, {:appmon_info, :handle_info, 2, [file: 'appmon_info.erl', line: 276]}]}}}
    appmon_info.erl:308: :appmon_info.do_work/2
    appmon_info.erl:276: :appmon_info.handle_info/2
    (stdlib) gen_server.erl:637: :gen_server.try_dispatch/4
    (stdlib) gen_server.erl:711: :gen_server.handle_msg/6
    (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
Last message: {:do_it, {:app, :pipeline, #PID<0.729.0>}}
State: {:state, #PID<0.729.0>, [], #Reference<0.3006373769.2547122179.177556>, [#PID<0.729.0>]}
 
12:48:14.863 [error] #PID<0.741.0> :proc_lib "crash_report/4" "proc_lib.erl" 508 
        Process :appmon_info (#PID<0.741.0>) terminating
** (MatchError) no match of right hand side value: {:error, {:EXIT, {:badarg, [{:erlang, :element, [2, :undefined], []}, {:appmon_info, :check_sasl_ancestor, 2, [file: 'appmon_info.erl', line: 618]}, {:appmon_info, :maybe_add_child_sasl, 4, [file: 'appmon_info.erl', line: 590]}, {:lists, :foldr, 3, [file: 'lists.erl', line: 1276]}, {:appmon_info, :do_find_proc2, 5, [file: 'appmon_info.erl', line: 497]}, {:appmon_info, :calc_app_tree, 2, [file: 'appmon_info.erl', line: 450]}, {:appmon_info, :do_work, 2, [file: 'appmon_info.erl', line: 308]}, {:appmon_info, :handle_info, 2, [file: 'appmon_info.erl', line: 276]}]}}}
    appmon_info.erl:308: :appmon_info.do_work/2
    appmon_info.erl:276: :appmon_info.handle_info/2
    (stdlib) gen_server.erl:637: :gen_server.try_dispatch/4
    (stdlib) gen_server.erl:711: :gen_server.handle_msg/6
    (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
Initial Call: :appmon_info.init/1
Ancestors: [#PID<0.729.0>, :observer, #PID<0.711.0>, #PID<0.82.0>]
Message Queue Length: 0
Messages: []
Links: [#PID<0.729.0>]
Dictionary: []
Trapping Exits: true
Status: :running
Heap Size: 10958
Stack Size: 27
Reductions: 115365

For completeness, this is more or less what I have:

defmodule Server do
  ...
  
  @impl GenServer
  def init(args),
    do: {:ok, State.new(args), {:continue, :load_pipeline}}

  @impl GenServer
  def handle_continue(:load_pipeline, state) do
    Task.async(fn ->
      repo = Application.get_env(:database, :bla) |> Keyword.fetch!(:repo)

      repo.transaction(
        fn repo ->
          # Do some work with streams that can take some time
        end,
        timeout: :infinity
      )
    end)
    
    {:noreply, state}
  end

  ...
end

Can I do something to help fix this issue?

Thanks.