Hi, we are currently running on a single node and due to scaling challenges (good problem to have!) we are looking at ProcessHub to move to a multi-node setup.
Here is the meat of our code that uses DynamicSupevisor and Registry:
@doc """
Start a child process or return an existing one by the given key
- If the process is already exists for the key, it is returned
- If the process doesn't exist for the key, it will be created with config in `{mod, opts}`
"""
@spec start_child(
supervisor(),
term(),
{module(), keyword()}
) :: pid()
def start_child(supervisor, key, {mod, opts}) do
# the registry is actually the name of the supervisor
registry = supervisor
case lookup_child(registry, key) do
# Process already exists, just return it
pid when is_pid(pid) ->
pid
nil ->
{:ok, dynamic_supervisor} = Registry.meta(registry, :dynamic_supervisor)
via = {:via, Registry, {registry, key}}
# The child will need to be registered with a via tuple so that we
# have a stable process name to reference
opts = Keyword.merge(opts, name: via, restart: :temporary)
case DynamicSupervisor.start_child(dynamic_supervisor, {mod, opts}) do
{:ok, pid} -> pid
{:error, {:already_started, pid}} -> pid
end
end
end
If I wanted to swap to using ProcessHub, what things would I use to replace DynamicSupervisor and Registry?
