Agent "Let it crash"

Questions / Help
,
1

I have the following simple Agent

defmodule ListAdd do
  use Agent

  def addToList(agent, value) do
    Agent.update(agent, fn list -> [value | list] end)
  end
end

How can I crash it so it gets restarted by the supervisor? I’ve been searching around and looks like you can simulate this using it’s stop function [stop(agent, reason \\ :normal, timeout \\ :infinity)](https://hexdocs.pm/elixir/Agent.html#stop/3) found in the documentation?

2

You can use Process.exit/2 to kill a process.

Process.exit(agent, :somereason)
Process.exit(agent, :kill) # kills process even if trapping exits

The following is from the built-in help.


                             def exit(pid, reason)

Sends an exit signal with the given reason to the pid.

The following behaviour applies if reason is any term except :normal or :kill:

  1. If pid is not trapping exits, pid will exit with the given reason.
  2. If pid is trapping exits, the exit signal is transformed into a
     message {:EXIT, from, reason} and delivered to the message queue of pid.

If reason is the atom :normal, pid will not exit (unless pid is the calling
process, in which case it will exit with the reason :normal). If it is trapping
exits, the exit signal is transformed into a message {:EXIT, from, :normal} and
delivered to its message queue.

If reason is the atom :kill, that is if exit(pid, :kill) is called, an
untrappable exit signal is sent to pid which will unconditionally exit with
reason :killed.

Inlined by the compiler.

## Examples

    Process.exit(pid, :kill)
2 Likes
3

I would say that “let it crash” is a statement about how unexpected errors should be handled, so a more realistic way to simulate a crash would be to call the update with a function with a bug that causes it to crash . For example you supply give a function that pattern matches on the incorrect data structure.

Why do you want your agent to crash? :slight_smile:

1 Like