Hi,

I’m writing my own toy implementation of a worker pool manager for learning purposes.

I do have one remaining issue (or at least only one I’ve identified ): when creating a new pool, a dynamic supervisor is used to start another (normal) supervisor that sits above all processes related to that pool. If I kill this supervisor, it doesn’t get restarted. Instead I get an error like

08:39:40.848 [error] GenServer #PID<0.4648.0> terminating
** (stop) killed
Last message: {:EXIT, #PID<0.4647.0>, :killed}
State: %PoolToy.PoolMan.State{idle_overflow: [], monitors: :"monitors_#PID<0.4648.0>", overflow: 0, overflow_max: 0, overflow_ttl: 0, overflow_ttl_timer: nil, size: 2, spec: PoolToy.Worker, sup: #PID<0.4647.0>, waiting: {[], []}, worker_sup: #PID<0.4649.0>, workers: [#PID<0.4652.0>, #PID<0.4651.0>]}
 
08:39:40.849 [error] GenServer #PID<0.4649.0> terminating
** (stop) killed
Last message: {:EXIT, #PID<0.4647.0>, :killed}
State: %DynamicSupervisor{args: [], children: %{#PID<0.4651.0> => {{PoolToy.Worker, :start_link, :undefined}, :temporary, 5000, :worker, [PoolToy.Worker]}, #PID<0.4652.0> => {{PoolToy.Worker, :start_link, :undefined}, :temporary, 5000, :worker, [PoolToy.Worker]}}, dynamic: 2, extra_arguments: [], max_children: :infinity, max_restarts: 3, max_seconds: 5, mod: PoolToy.WorkerSup, name: {#PID<0.4649.0>, PoolToy.WorkerSup}, restarts: [], strategy: :one_for_one}

I don’t know what code would be relevant to include here, so I’ve pushed the current state to github: GitHub - davidsulc/pool_toy: A toy worker pool implementation aiming to teach about process supervision trees · GitHub You can download the code from https://github.com/davidsulc/pool_toy/archive/master.zip

Here are the steps to reproduce the issue (within the pool_toy directory):

# start the app
iex -S mix

# start a pool named :pool_a with 2 workers
iex> PoolToy.start_pool(PoolToy.Worker, 2, name: :pool_a)

# start the observer
iex> :observer.start

Within the applications tab of the observer, right click on the direct child of the named Elixir.PoolToy.PoolsSup process (which will have no name, just a pid) and kill it. I would expect the process to get restarted by the Elixir.PoolToy.PoolsSup dynamic supervisor but that’s not the case. Why?