I have an Agent which processes a tree of TOML files on startup,
turning it into a tree of maps. Occasionally, while debugging,
I’d like to reload this tree. So, I set up a “/reload” page to:
get the current time
tell the Agent to print a message and then kill itself
get the current time
calculate the duration
render a “reload” page
Although the message is getting printed, the “reload” page is
not appearing. The browser says:
This page isn’t working
localhost didn’t send any data.
Suggestions? For the relevant code, see this gist:
Tracing RefData.Server.start_link/0, I found that it isn’t getting run after the exit. So, I probably have a problem in the Supervision setup. I will look into this, but meanwhile, here is a gist of my current setup:
It’s probably better and more reliable to restart the child using the supervisor. I don’t remember how Elixir Supervisors assign the id to their children, but this is generally how you’d do it:
The reason you might be getting no data sometimes is:
def reload(message) do
IO.puts message
pid = self() # <--
Process.exit(pid, :kill)
end
self() is the pid of the calling process. I think you’re crashing the connection and not the agent. The reason sometimes data does get returned and rendered is because Process.exit/2 is asynchronous.
[error] #PID<0.555.0> running PhxHttpWeb.Endpoint
(connection #PID<0.554.0>, stream id 1) terminated
Server: localhost:4000 (http)
Request: GET /reload
** (exit) exited in: GenServer.call(Supervisor,
{:terminate_child, RefData.Server}, :infinity)
** (EXIT) no process: the process is not alive or
there's no process currently associated with the given name,
possibly because its application isn't started
Looking over my startup code, I can’t see anything that differs much
from the way PhxHttp does things…
